This lengthy oneshot comes with a bit of a confession. I'm generally very anal about canon compliance, and as such AUs aren't really my thing, whether it be writing or reading them. However, I do have a soft spot for fix-it fics in which Koro-sensei survives. Yes, I'm happy with the ending of AssClass as it is canonically and I respect its significance, but I like to indulge myself sometimes and think that the teacher we all wished was real could have went on to live a long and happy life after graduation. So when Shiranai Astune suggested this prompt to me- that Koro-sensei be cured and return back to a normal human, I jumped at the opportunity.

Thank you for the request, Shiranai Astune. This was quite emotional for me to write.

Disclaimer: I do not own Assassination Classroom. If I did Yanagisawa would have died at the end.

It was over.

In reality it only took a few minutes, but to 3-E Class of Kunugigaoka Junior High, it felt like a lifetime.

Their beloved teacher, the one who understood them on a level no other educator or authority figure ever did before, was gone.

It happened with a gentle push of one of those anti-sensei knives, in the hands of the student no one would have expected it from a year ago, or even six months ago.

The teenaged assassins were now surrounded by glowing orbs of yellow, that slowly floated towards the crescent moon and the shining stars.

And then came the waterworks. First it was Nagisa, then he was followed by Kayano, then Sugino, then Isogai and Maehara and Kataoka. Okuda reached for the pack of tissues in her pocket but realized that she had left them at home. Karma looked down at the ground, as if to hide his tears from his classmates. Kurahashi reached over to embrace Hara, and Yada and Okano joined in. Even Terasaka and his 'goons' Yoshida, Muramatsu, Hazama, and Itona were contributing to the atmosphere.

A shooting star shot by. Amidst their tears and heartbreak, none of them noticed.

Koro-sensei felt a vague sense of... being. Wasn't he supposed to be dead? He expected to either feel the scorching fires of hell or maybe even see a blinding white light and be overcome with the sense of peace. But he knew he clung to life. When he opened his eyes, or what felt like they should be his eyes, he saw his students, sitting on the ground hysterical over his passing. And Koro-sensei was floating up, up in the air. He tried to shout. No, students, I am still here! But he now had no mouth.

He tried to push down, but it felt like some force was pushing him upward. He flailed his tentacles, but stopped abruptly when he saw one of them. Or rather, when he didn't see one of them.

He looked down at the rest of his body. There was nothing at all. He was invisible. Even his clothes were on the ground, abandoned in death. Maybe this was what dying felt like after all. Maybe he was about to enter the afterlife.

Koro-sensei saw a shooting light out of the corner of his eye. A shooting star. He knew, he'd seen plenty in his life. Then the blackness came.

When Koro-sensei regained consciousness, he was lying face down on the ground right outside the E Class building. It was... The middle of the night, he guessed? Well, it was dark out, and no one was there. Was this some sort of afterlife? He scoured through the school building first, and was greeted by the sight of his clothes. He didn't even realize until now that he hadn't been wearing any. With a blush, he got dressed at Mach 20, and silently thanked whoever decided to fold them up nicely and place them on his desk.

The main classroom, the storage room, the broom closet, the teacher's lounge, the bathroom, they were all vacant except for the items that were always there. No sign of his pupils. Koro-sensei reached for the phone in his pocket.

March 15, 2016. 2:13 a.m.

But I was supposed to be killed by midnight two days ago! Koro-sensei was in a confused panic. He distinctly remembered his class holding him down, Nagisa being the one to deliver the final coup de grâce. And if for some reason that failed, the lazer was supposed to fire and disintegrate all tentacle material within that field. There was no way he could be alive right now. This was clearly some sort of post-mortum dream.

He poked and prodded himself with his tentacles. Counted backwards from one hundred. Grabbed the nearest book and read a page. Sang a song. Lastly, he grabbed one of those anti-him knives and pushed it into his skin.

Or rather, he tried to. His flesh didn't give way or melt at all. It was not in the least bit damaging. It just sat there. What was this?! Koro-sensei knew the only way to figure it out, and it was also the first thing he needed to do in any emergency: talk to his students.

Koro-sensei thought of sending a mass text, but realized quickly that they all needed to hear this in person. So starting in the morning, he flagged each of them down one by one. He went into town in his disguise, knowing they would still be on break and would probably be home alone. He knocked on Karma's window at the crack of 8 a.m., and nearly gave the poor boy a heart attack. Hara was making breakfast and even offered him some (he happily accepted). Kanzaki broke down crying and hugged him (he patted her shoulder). He told them all the same thing: meet up at the E Class building at one a.m.

And they all listened. All twenty-eight faces appeared in the classroom that afternoon, most red with tears. A new wave of crying broke out when they were confronted with their beloved teacher once again. Luckily, the ever-prepared Koro-sensei had boxes upon boxes of tissues lying around "just in case". When all had calmed down, the elephant in the room was acknowledged.

"So how are you still alive?" Terasaka asked, flatly.

"I don't know. I felt like I was floating, then I woke up about twenty-seven hours later on the field..."

"Yeah, this lacks a medical explanation." Takebayashi adjusted his glasses. "Even if you could somehow escape our grip without us noticing, you shouldn't have been able to escape the anti-tentacle barrier."

"If you're shocked by that, check this out." Koro-sensei grabbed an anti-him knife with his bare tentacle. His students' jaws hung open.

"Y-You're not hurt!?" They simultaneously yelled.

He shocked them yet again by driving the knife into him. It bounced off of his tentacle and fell onto the floor, not causing so much as a dent in his skin. He grabbed a loaded anti-him gun and fired a few rounds at his head. They too bounced and left not a single mark.

"W-WH-WHAT!?" E Class was glad that the government officials were not inspecting the area at this time of night, because they would have certainly come running if they had heard.

Okuda was the first to enunciate an actual statement, which was a shock in of itself. "Th-there has to be some kind of scientific explanation! Maybe you have developed an immunity to anti-tentacle attacks!" Okuda's classmates were taken aback by her passionate outburst. "I-I don't know exactly what it is or how it happened but I'm going to figure it out! This will be my life project!"

Koro-sensei slithered a tentacle over and gently patted the violet-eyed girl on the head. "There there, Okuda. You don't have to prioritize my mystery over your future."

"Koro-sensei," She sniffled for a minute, then continued. "You remember what you put in my and Takebayashi's yearbook? Even after death- or at least, what we all thought was death- you helped us all in a way we could never repay. But this is the closest I can get to doing so."

Life went on, albeit shakily. Koro-sensei hid in various deserted locations around the world until E Class was able to purchase the mountain "for their own use", meaning Koro-sensei could live there and would never be discovered by unwelcome guests. The government officials were no longer there. But soon spring break had to end, and time stopped for no octopus.

Koro-sensei couldn't come to his own students' graduation, or to the welcoming ceremonies at their new high schools. He wasn't even able to see if the boys reciprocated the girls' Valentine's Day gifts on White Day. He had to lay low for a while. As for his class, they were still haunted by the ghosts of that year, of those 365 days they spent with Koro-sensei and with each other. So their high school lives began in a somber, gray mood in spite of the bright pink sakura leaves decorating the skyline.

Koro-sensei was now sitting in the old E Class building. Birds had perched on his many tentacles. With a free tentacle, he grabbed some birdseed to scatter on the ground, sending the birds in a frenzy over the food. The octopoid creature sighed. As he had no job and therefore no money, he had been eating things he found in the woods. What do I do with my life now...?

Koro-sensei wandered around his classroom. Not at Mach speed this time. Just a leisurely stroll. There was still no AC in this shack, and there would be no heating in the winter. The desks were so bare without his precious students to fill them. The building so silent without their laughter. Even if he were to have accepted Principal Asano's offer to teach E Class again, the E Class system was terminated and Asano was forced to leave schools. Koro-sensei's career was over.

Koro-sensei's tentacle feet lead him to the teacher's lounge. His eyes fell upon a bookshelf loaded with as many books as he could fit in them. Biology textbooks, Charles Dickens novels, guidebooks from the trips to Kyoto and Okinawa. He observed how big the guidebooks he wrote were. Well, I had to be thorough. And my preparedness did save my students... He chewed on a pinecone.

"I sure do love to write," He spoke to himself (hey, no one around to judge but God). "If I could do that for the rest of my life I'd be perfectly happy."

Koro-sensei dropped his unorthodox 'snack' when he came to his revelation.

That was it.

Koro-sensei's face was striped yellow and green. The colors started revolving like a barber's pole. He shot around the classroom, grabbing everything in his line of sight that might even remotely help him with his next endeavor. A pen, of course. Loose-leaf paper. A binder already overstuffed with old classwork. A diary he had bought but only wrote in sporadically. A ruler. A coffee mug (he forgot that it was full and hot water splashed all over his feet).

He sat at his desk and thoughts began spilling out onto the loose-leaf paper. A dramatic story about an assassin who was betrayed by his apprentice. He killed his apprentice's father, and the apprentice never truly forgave him for that. Now he was a writer in some abandoned countryside town in rural Japan, and he found redemption when he was befriended by the teacher of the local school. Ideas came unbidden from his mind to the paper. He had his diary open in another tentacle, pulling ideas from the trivial things that happened to him on Wednesday, October 28th 2015. By the end of the night, he had four hundred pages worth of notes.

Wait 'til they see this, Koro-sensei yawned. I just can't wait... He fell asleep at his desk with thoughts of assassins and love in his head.

About three or four weeks later, joy was restored the former assassination classroom. What had happened finally sunk into the fifteen year-olds' brains. The world was safe, they got the reward money (though they sent most of it back), and their beloved teacher was still there and they could see him at any time! This was every good outcome they had hoped for. That meant party. In the old E Class building, of course. No alcohol, they were all good law abiding citizens. No loud music, and not at one a.m. Nothing like the parties they had been invited to recently, in high school. Just some clean G-rated fun with old friends.

All twenty-eight kids were crowded in a circle, laughing and catching up. Sugino was a treasured member of his school's varsity baseball team, and their fifth game was coming up soon. Karma had managed to keep his anger under control when Asano Jr. got a higher score than him on the recent exams by two points (they were both upstaged by a new rival). Nagisa was only mistaken for a girl nine times so far. Isogai had already gotten fifteen love letters from girls at his new school, but they mostly started backing off when they got the idea that Kataoka had dibs on him. And there were a bold few that responded by giving love letters to them both...

Koro-sensei for once did not anticipate an assassination attempt. It was from Itona. Just a quick jab with one of those anti-sensei knives. Koro-sensei fled from it and grabbed his student's wrist. It was a matter of muscle memory, really.

Koro-sensei snatched it with a bare tentacle. "Remember, they don't work on me anymore." He mocked, his face yellow with green stripes. All eyes in the room were on them.

"I know... But this is our duty." There was silence as the class processed what Itona was saying. "I came to this class to kill you, and that's what I'm going to keep trying to do." Itona stole red bean jelly from Koro-sensei's desk, but it was snatched back immediately. "Old habits die hard, I guess."

"You are not wrong, Itona." Koro-sensei sighed while brushing Itona's hair. "Assassinating me was the first assignment you were given in this classroom. And you remember your other assignments? If you didn't finish them on time, I expected them to be handed in late."

"So..." It was Isogai who broke the silence first.

"So if you continue to try to kill me, it will just be an extension of your work last year in this classroom."

"But you really live up to your name now that those weapons don't work on you! Do you know about any weaknesses you still have?" Yada cried. She didn't want to go through this again.

"I admit I don't, but never say never. I'm sure you'll find something." Koro-sensei saw that his students had conflicted expressions. "... But you can make that decision individually. If you don't want to kill me again, and you have the viewpoint that you did your job already that night, that is up to you. Either decision is an admirable one." He ate his red bean jelly.

The class still did not respond.

"Well whatever, you don't have to think about such heavy issues right now! This is a party! Let's play a game!" He went to the closet to look for boardgames, but found that he had none. "The government officials must have taken them all when they raided the room." Koro-sensei addressed the room, closing the closet doors.

"No, Karasuma and Bitch-sensei took them." Ritsu's voice came from Koro-sensei's phone. "They said they were running out of things to do."

"Already?"

"Uh, we have a bottle, let's play-" Yoshida was grasping at straws for ideas.

Karma and Nakamura exchanged an evil look. "We could play truth or dare..."

"Ah, E class! May I have your attention!?" Now was the best time to make his announcement, while it would distract from the devils' ideas for party activities. "I have decided what to do with the rest of my life. That really does lead to the question of how much longer I am going to live, but alas, I digress."

Okuda piped up. "I'll figure it out, Koro-sensei!"

"I have complete faith that you will, my dear student. Anyways, I'm going to start writing a book!"

Hazama's and Kanzaki's faces lit right up. "Can I read what you have so far?" Kanzaki was glowing.

Hazama's expression became sullen after a minute. "You know what, you probably wouldn't write my kind of literature."

"I haven't started yet, but I have a few ideas floating around in my head. You can see my notes." Koro-sensei whipped out a huge binder that must have weighed ten pounds. "Just a few little inspirations I had making my tea this morning. It's nowhere near done..."

The class collectively rolled their eyes. This will be the most long-winded book ever written, was the unspoken sentiment that ran through all their heads.

The octopus got right to work on his first book as soon has the students left.

Koro-sensei's first book was published towards the end of the following year. He chose a pen name, "Kogoro Senuma", and refused to let pictures be taken of him. If anyone lingered on his image, they might figure out he wasn't exactly human. He turned away all requests for interviews. He had to remain mysterious. The novel was picked up by the first publisher he submitted it to. The Lone Assassin was an immediate bestseller, and the critics adored it. His students all pre-ordered it and got their copies signed on the day of its release. However, it took them a full year to finish reading it.

"It never ends!" Irina remarked when Koro-sensei handed her a signed copy.

"I still haven't finished that book of advice he gave us when we graduated..." Okano struggled to carry her copy.

"Maybe I'll star in the film adaptation." Kayano wished aloud, dragging the book.

Koro-sensei received visitors for other reasons besides book-signing and assassination. Tutoring was one of them. "Once a student of Koro-sensei's, always a student of Koro-sensei's," he would say. Maehara still needed help in English and Japanese, and would come looking for advice about how to handle girls. Muramatsu wanted someone to taste test new ramen recipes he created. And Hayami and Chiba still came by to practice target shooting while reciting historical facts that their sensei forced them to memorize that year.

"Speak up, I can't hear you over the gunfire. In what month did the October Revolution occur?" Koro-sensei dodged their bullets, not that it mattered since he wasn't harmed by them anyway. He was just showing off.

"November!"

"And where did the European renaissance begin?"

"Italy!"

"What is Koro-sensei's favorite flavor of ice cream?"

Chiba and Hayami responded with more gunfire.

Koro-sensei received another visitor a few days later. He dodged a knife strike- an anti sensei knife, of course. "Karasuma! Nice to see you!" He got right to work plucking his eyebrows and massaging his temples.

"Still in that habit, huh..." Karasuma sighed.

"Only because you still look like you haven't slept in years." Koro-sensei giggled. "You should really take some time for yourself. You and Irina."

"That's actually why I'm here." He pushed an envelope into Koro-sensei's tentacles. Gingerly, the octopus opened it. It was a slip of pink paper decorated with cherubs with cupid bows shooting hearts.

Save the date

You are formally invited to the wedding of Tadaomi Karasuma and Irina Jelevich

August 18 2018

It was too much for him. Koro-sensei cried. A steady drip of tears, as was often the case when Koro-sensei's class impressed him. "K-Ka-Karasuma! I never knew you two were engaged! I have to add this to my new book!" Koro-sensei returned in the blink of an eye with a massive notebook and about seven different pens and pencils.

Karasuma glared, then rolled his eyes with a sigh. "This is the reason we didn't tell you. And if you feel you must."

"Remember how I asked you for an interview for the last yearbook? The request is still out there."

"No." Karasuma stormed out.

"It'll only take like seven hours!" The yellow octopus scrambled after his former colleague at Mach speed. "Okay maybe a bit more, but-"

"No."

The wedding took place at the nearest Russian Orthodox Church, as there was no Serbian Orthodox Church anywhere to be found. It was located on a mountainside with a wonderful view of Tokyo. Koro-sensei arrived extra early. Koro-sensei was from the Phillipines, a majority Catholic nation, so while he wasn't raised with the faith, he knew enough to dip a finger in the Holy Water and draw the sign of the cross before entering.

The church was spacious inside, and quite well-ventilated in this late summer heat. He took a seat next to Isogai and Kataoka. All of former E Class was attending this ceremony, and they all dressed in the best clothing they could find.

"Uh, Koro-sensei?" Isogai raised his hand in spite of not being in a school environment.

"Yes Isogai?"

"Please do try to be more... subtle."

Koro-sensei was puzzled by what exactly that meant. Isogai pointed to the ground, and the teacher's tentacles were indeed slithering and twitching. He was supposed to be a human, but human limbs did not slither and twitch like that.

My disguise was supposed to be flawless! Koro-sensei silently gasped. He found he could not quell the movement, so he just opted to sit with his 'legs' tucked underneath the pew rather than out in front. He wondered for a brief moment if he was getting ill, but forgot it all once the music started playing and the doors opened, revealing an ivory-clad Irina on the arm of one of the priests who was acting in the role of her father for the day.

The wedding was a beautiful event. Tears were shed (and not just Koro-sensei's) when Karasuma kissed his bride. The reception was at an upscale banquet hall inauspiciously located in the valley that the mountain overshadowed. Koro-sensei's heart was hit with a pinch when he pictured himself and Aguri doing what Irina and Karasuma were doing now. He excused himself to go outside for a few minutes and stare at the bright blue, cloud-dotted sky.

"Koro-sensei?" Nagisa's voice tore him out of his reverie.

"Oh, hello there Nagisa. What do you need?"

"I just noticed you left. Are you okay?" He approached his old teacher.

"I was just... thinking about Yukimura-sensei. I wanted to do this with her someday. But of course, you know how well that went..."

There was a pause. Nagisa shuffled around, clearly looking for something to say. "Koro-sensei... I have an idea."

"Hm?"

"Of course, we'd have to ask Akari- I mean Kayano... But she has a lot of pictures of Yukimura-sensei. Maybe she can make some copies and give them to you."

"Thank you, Nagisa... That would be wonderful." The octopus wiped away another tear.

"Don't thank me, thank Kayano." The bluenette chuckled. "How's the writing going?"

"Working on a new book already." Koro-sensei leaned on the fence. "But enough about me. Are you getting along with your family?"

"I wish I could say I am." Nagisa's parents had tried to get back together, at Koro-sensei's suggestion, but that didn't last long. "A couple of months ago my mom had a breakdown over me wanting to be a teacher and kicked me out. I'm living with my dad now." Nagisa stared at the ground. "My mom and I made amends when she came to see me on my birthday last month, and she wants me to move back in with her." His pigtails were blowing in the wind. "But I don't want to. I don't want to live with my dad either, he's still not there for me emotionally."

"What then, do you want to do?"

"Karma said I could move in with him. I want to, but I don't think the courts would allow that."

"Do you want me to talk to them again?" Koro-sensei plucked flowers from the hillside, and wove them into his robe.

Nagisa spent a great number of seconds inhaling, then let it all out in one breath. "I do, but I don't know what you'd say or what that would accomplish. I don't know that to do..."

Koro-sensei handed a flower to Nagisa. "Remember what I told you, Nagisa. You must express your wishes clearly and communicate with your parents."

"I did, and my mom kicked me out." Nagisa's pigtails drooped.

"And I think you're better off without her negativity. What I mean is that you should tell your father that you're feeling ignored by him. Maybe he doesn't realize he's doing it. Maybe he just doesn't know how to express his affection for you. He tried getting back with your mother for your sake. He does care about you, he just hasn't been in your life for so long, that now he probably doesn't know how to be." Koro-sensei considered making a flower crown for Nagisa to wear, but realized that would probably give him flashbacks to his mother's abuse.

Nagisa gave him a big cute smile. "Thanks, Koro-sensei. I will. It's probably best I don't move in with Karma anyway. I'm sure he'll put ice packs on my feet when I try to sleep."

Koro-sensei was surrounded by photos of his would-have-been wife. They were spread out all around him while he wrote paragraphs of his new story. Baby Aguri, twelve year-old Aguri holding her newborn sister, Aguri's college graduation. Pencils were worn out and broken, strewn about. He couldn't find anymore writing instruments, so he switched to typing on his computer. You will be in this one too, Aguri. Koro-sensei thought as he typed at approximately five hundred words per minute. You'll all be in this one.

Koro-sensei's next book, which hit the shelves the following winter, was a tale of the many romances in a classroom in a remote village. The Japanese teacher was desperately infatuated with the History teacher, but he refuse to look her way. There was a boy with an unrequited love for the prettiest and most popular girl in class, who was otherwise pursued by awful men. The school playboy was oblivious to a softball player's crush on him, because she expressed it by being aggressive and rude. The class delinquent had a close relationship with a shy nerdy girl who was fascinated by books and spent all her time in the library, and an effeminate boy kissed a short girl in front of the class to stop her rampage because the cafeteria was out of pudding.

Of course, E Class knew where all this came from, and collectively sweatdropped when they all read it. Although Koro-sensei sure did take a lot of liberties. These characters were high schoolers, and the climax of this story was the college entrance exams. There were dates between characters whose obvious basis's never even talked, even Nakamura and Kimura were paired together! Where did that come from?

"I thought they'd make a good couple!" Koro-sensei defended himself when his former students confronted him at his residence. "You knew I was writing that book all year! Why are you shocked I published it?" He dodged about fifty knife strikes.

"I don't want the world knowing I play air guitar in the middle of the woods at night!" Mimura exclaimed, grabbing an anti-sensei gun.

"And how come I didn't get a girlfriend in this story? Even Takebayashi got paired with human Ritsu!" Okajima was the most angry of them all.

"Hey what's that supposed to mean?" Takebayashi thought of defending Koro-sensei, but decided to join in with the rest of them, throwing an anti-sensei knife.

Koro-sensei grabbed the guns from his students at Mach speed. "You don't play air guitar in the middle of the woods at night, Mimura, Kouichi Momura does!"

The students were unimpressed. Anti-sensei knives flew at him.

"You can put me in your story!" Irina spoke up over the chaos. "I don't mind the attention."

The students graduated from high school the following March, on a bright and sunny day. Koro-sensei attended all of their ceremonies, though attending all of them meant that he could only spend a few minutes at each one. He figured it took each student two minutes to walk to the stage and receive their diploma, so he calculated exactly when each of E class would get theirs, factored in travel time, and managed to see every one of them get their diplomas. Koro-sensei's tears flowed freely from his beady eyes. "My children!"

College began a few weeks after. Koro-sensei tried the same deal with opening ceremonies too, but found that security was tighter and that most colleges didn't let him onto their campus without an I.D. on moving day. After making a mental note to get a fake I.D., he called each student over the following few days to have four-hour conversations. He wanted to know everything about what the campus was like, how they were getting along with their roommates, if his lessons prepared them for college work... Most did not have answers yet, it was only three days into their college life!

"Work that into your next novel," Said Kataoka as she finished the tale of how she and her new roommate ended years-long prank war between the two floors of their dorm using a slingshot and a one thousand grains of rice.

Akari Shiota, formerly known as Akari Yukimura, known to the world as Haruna Mase, and lastly known to Koro-sensei and his students as Kaede Kayano, was giving birth in secret at the Takebayashi General Hospital. The doctor leisurely strolled around the room, in no rush to look for the epidural because this baby was taking its time. When the doctor heard a voice coming from outside the hospital, he almost dropped his needle.

"Go! Go! Kayano! Go! Go! Kayano!"

It seemed to him like about a dozen identical looking pale men with round heads and very thick limbs were waving pom-pom's around in cheerleader outfits... For someone named Kayano. In this mid July heat wave. The doctor rubbed his eyes and muttered to himself. "Maybe I should try decaf."

His patient's head shot right up "K-Koro-sensei!" She gasped. "For us-" Her words were cut off by her screams of pain as another contraction hit her.

The nurse looked the doctor in the eye. "The baby's coming now."

Nagisa was pacing back and forth in the waiting room. It had felt like hours, his heart was pounding so hard he could hear it. Before he knew it, his former teacher, cloaked in a not-so-convincing disguise, was next to him.

"Ahh! You scared me there!"

Koro-sensei patted Nagisa's head. "I know you're nervous. So am I. Obviously not to the extent that you are, but if it is okay for me to do so, I like to think of this as my niece. Though I envy that I never got to be in your position with Aguri Yukimura, I'll stay with you as long as I can."

Twenty hours later, baby girl made her grand entrance into the world. By the time the new family got home, Koro-sensei had already stocked the house with gifts, toys from all around the world, an over-abundance of baby supplies that they already had plenty of, had cleaned the house, and cooked dinner for the both of them. Less than a week later, he was on their couch, cooing over and bouncing the sleeping baby. A new phase in Koro-sensei's life had begun, and he already loved it.

It was now April of 2026. It had been ten years since E Class had graduated. Days began to feel like seconds, and with every passing year Koro-sensei felt himself changing. Another shift was taking place, it felt much like when he was first injected with tentacle cells. He was slowing down significantly; he guessed he could only move at about Mach 10 now. His limbs were no longer soft and squishy; they were now taking on a stiffer quality. His face did not always express his emotions with color and shapes. He always felt fatigued, no matter how many hours he slept. He couldn't go to a doctor, obviously. So he mostly just suffered though it, figuring this was just another phase of being a tentacle creature.

Koro-sensei had decided to take a walk outside to take his mind off the discomfort. He was having trouble with this particular chapter of his newest book. No matter what he wrote, it just did not sound right. A song he once heard echoed in his head. The colors I chose are not at fault. The words he chose were not at fault either. He drug his tentacles through the tall grass, as he had not cut it in ages.

A shooting star shot by, decorating the night sky with a streak of brightness. If one were to look at the sky, it would stick out like a yellow-orange scar on the flesh of the dark atmosphere. But no one in Kunugigaoka did. No one but Koro-sensei.

That summer, another reunion was held. On this particular night, the moon was full and bright- well, as full and bright as it could be given that it was 30% of its former self. There were no stars out. E Class had rented out the same banquet hall that Irina and Karasuma's wedding reception was held in.

Many announcements were made that night. Okajima finally met a girl (and she's human!), Kurahashi had just finished veterinary school, and Sugaya's paintings were now being showcased in the largest museum in Tokyo.

Koro-sensei cried. This time it wasn't a steady drip of tears, but a dam breaking and sending floodwater everywhere, figuratively.

"Ew! Koro-sensei you're getting your snot all over the floor!" Okano yelled, grabbing for an anti-sensei gun she kept in her pocket. Kataoka disarmed her.

"There are children present!" The former class rep scolded her.

"I'm sorry!" His sobs became more and more dramatic. His students were truly all grown up now, making major achievements and starting families (Chiba and Hayami had just celebrated their one year anniversary). They were becoming men and women he was proud of. Koro-sensei cried so much that he had a sore throat the next morning.

Later that fall, Koro-sensei was struck with a terrible tragedy he had never experienced before.

It haunted him every waking moment, and he could not even escape it in his dreams. It loomed over and ruled every event in his life, no matter how mundane. He could not think about anything else. He prayed that this torture would end soon; he wasn't sure how much more of it he could take.

Writer's block.

He thought it would be a temporary thing, but it went on for months and months. When he woke, the only thing on his mind was exactly how empty it was. He watched the news every morning. He read his old diary entries. He thought back to all the people he killed, and how, when, where, and why he did it. He called and visited each of his students to ask about their lives, thinking that maybe that would stoke the fires. But nothing did.

Defeated, Koro-sensei picked up the book that Hazama had lent him from her library. The Stand by Stephen King. And in English, no less. He was a very well-read octopus, but he hadn't gotten to this one yet. He munched on the swiss rolls Hara had brought him, reclining in the rocking chair Itona had built for him. Maybe reading more would give him inspiration.

It did, and his next novel was soon in progress. A horror story about an evil scientist who preformed experiments on prisoners. One of the prisoners, a convicted murderer, escaped and began to go through a terrible transformation. He became a tentacle monster!

"The Lovecraft influence is obvious," Hazama noted when all the students went to get their copies signed.

"Koro-sensei, how could you write that? I've been having nightmares for days!" Kurahashi cried.

"I write about what I know, and that's pretty much what happened to me!" Koro-sensei dodged the copies of the book that were thrown at him. The books were left there, and Koro-sensei personally delivered them to each student's house with hand-written notes about taking care of important property.

The shift happened the same way it did the first time, many years ago: slowly at first, then one abrupt change. Tremors started happening. He'd pick up his pen to write, but it would slip out of his tentacle before he could get a word out. He felt spasms in every part of his body. He would wake up at night suddenly and be unable to sleep again for days.

The final phase ended on a cold night in November 2029. It was one of those many nights that Koro-sensei was unable to sleep. He was reclining on the rooftop of the old E Class building, then a sudden pang hit him. It was indescribable. He had felt it once before...

Instinctively, he ran into the woods, searching for a cave or a big rock or something to hide under, because he knew what was going to happen. It felt like a million cramps seized his body all at once. He fell in the woods and could not pull himself back up, he was too busy fighting the pain. It felt like his internal organs were exploding and trying to claw their way out. Koro-sensei couldn't even scream. He was paralyzed.

A voice spoke up. One he hadn't heard in years. The tentacles. You wished to be weak... Your wish was granted.

Gradually, after what felt like an eternity, the tension wore away. Koro-sensei opened his eyes. His consciousness was back. He didn't even need to look down at his hands, but he did anyway. They were pale, flesh-colored, and- human. Four fingers and a thumb on each. He had two legs, two feet with five toes each, ankles, wrists. He ran a finger through his hair. It was silky and smooth. Koro-sensei pulled his phone out, opened the camera app, and turned it to selfie mode. He was right. Human Koro-sensei, the man once known as The Reaper, had returned.

In the night sky, across the Milky Way, a shooting star shot by again. It went unnoticed by the population of Kunugigaoka.

Well, this was awkward news to break to the rest of them. He posted in the group chat.

Koro-sensei: Everyone, come to the old E Class building as when you can. It doesn't have to be as a group, just see me as soon as possible. Something big just happened.

They came as a group anyway. The next afternoon, Koro-sensei was greeted by a knock at the door. He frantically addressed them through the door. "Just don't be too shocked when you see me." He took a deep breath and opened the door.

His students did not listen to his recommendation. They screamed.

"WHAT!" Koro-sensei was swamped by his students, now adults, hell one even had his own students. But to him, they were still his students.

He was poked by many fingers all at once. His hair was touched. He was pelted by questions.

"Can you feel that?"

"Are you still fast?"

"What was it like, to change back like that?"

"Sorry if I'm out of line saying this, but you are hot!"

The last one was, predictably, Nakamura, who had Skyped in from America to witness this. Koro-sensei tried to explain it to the best of his ability.

"I don't understand it either... I couldn't sleep last night, I started having those tremors I've been having as of the past few years. I knew what was going to happen, call it instinct, I guess? And then it just happened all at once. Like ripping a band-aid off."

Okuda looked like she was about to have a stroke. "I-I have to record this! This is a breakthrough!" She ran up to Koro-sensei, and the others made room for her.

Takebayashi followed. "Let's take his vitals. Koro-sensei, what time exactly did this happen?"

"Um... I don't know, midnight? One in the morning?"

"Was your heart pounding? Fever? Headache? Upset stomach?" While Takebayashi ran to the hospital to get medical equipment, Okuda asked him every question that came to mind. Ritsu wrote down the answers in the note app.

When the doctor returned, Koro-sensei was overwhelmed again when he was stuffed with thermometers. His fingers were pricked to measure his blood sugar. Everyone crowded around, taking in what their teacher's real face looked like.

"Can we still call you Koro-sensei?" Fuwa asked. "Or do you want to be known by your birth name? I mean, you're human now, and I'm guessing not unkillable anymore."

"I'm Koro-sensei to all of you. As far as you know, I have no birth name. And I think it goes without saying that I don't want to be called The Reaper."

Everyone agreed.

And so human Koro-sensei was reborn.

Koro-sensei had recently found himself babysitting lots of the children of his former students while they were at work. It was a perfect arrangement- they were safe with him on the mountain, and he got to know the people whose existence he awaited with baited breath while making some extra money in between books.

His "nieces", the daughters of Nagisa and Kayano, were fascinated with tales of the assassination classroom. He tried to keep it as G rated as possible, believing that some of the stories were not his to share. Kurahashi's three year-old daughter would crawl around in the grass, looking for bugs, her one year-old brother often trailing behind. Chiba and Hayami's four year-old son was always the most well-behaved kid in the room, yet his two year-old sister was currently running around the room chasing her babysitter.

"Koro-sensei!" She pulled a finger out of her mouth, grabbing at his newly formed hands.

Koro-sensei picked her up and twirled her in the air. "Midori-chan! Time to play hide and seek!" Kanzaki's two-year old daughter joined in, tickling Koro-sensei's feet.

Koro-sensei collapsed in a fit of giggles. He was glad that Hara was on vacation with her two sons, because they would have joined in and Koro-sensei would not have been able to get back up when he heard footsteps in the hall.

Koro-sensei grabbed the anti-sensei knife that was launched at him. The children scattered, having apparently found a really interesting ladybug in the corner. "I told you no assassination attempts in front of the kids! But nice try, Karma."

Karma Akabane, formerly the biggest troublemaker of E Class, and grown into a tall, handsome, and successful young man. Now, as a bureaucrat, he followed the rules... mostly. "Hehe. Just wanted to see if you were still on top of things. Anyways, I'm here to pick up my nieces." He beckoned to Nagisa and Kayano's daughters, but they were too busy putting messy braids in the younger girls' hair.

"You can all stand to stay for a moment. I must say, the wedding was beautiful, Karma. Did you appreciate all the wedding gifts I sent you?"

"Rice cookers are great and all, Koro-sensei, but I don't think Manami and I need four of them." Karma laughed.

"But what if you have a dinner party!?" The former octopus comedically overreacted. "Anyways, it took you two long enough to tie the knot."

"That's what happens when you want to marry a woman with three Phd's."

"When are you going to give me another little addition to my makeshift daycare?"

"Not for a while. She's still in med school, after all."

"Just make sure I'm the first to know when it does happen, okay?" Koro-sensei picked up ten month-old Nobuhiko Sugino before he crawled out of the room.

"No doubt." The three girls ran towards their 'Uncle Karma'. The youngest handed him a finger painting of Koro-sensei.

"Sugaya would be jealous." Karma laughed, then left with the girls, leaving Koro-sensei to fend for himself against a mob of toddlers.

He managed to convince the kids to take a nap, which left him some time to clean up the room.

In a box in the corner, a stack of postcards from Nakamura were gently laminated and alphabetized. London, New York City, Paris, Rome... He thought of putting them all in a binder or maybe even placing them on a big map on the wall for the children to see when they came over.

Deciding to do the latter, Koro-sensei got out the glue, searched for a world map somewhere in this room (there had to be one here somewhere, probably in one of those bins he packed away), and cursed the fact that he could no longer move at Mach 20.

It was 2034. Koro-sensei was in Manami Akabane's living room, going over the results of her 11 years of research. It turns out that if the explosion of anti-matter tentacles can be avoided, at some point their effects will be reversed and die. "But you already knew that." The scientist adjusted her glasses. Koro-sensei and her former classmates still called her Okuda, though it wasn't her last name anymore.

"Yeah. Any other interesting finds?" A pot of green tea was on the table. Koro-sensei poured out some of it into his cup, hoping that Karma hadn't poisoned it. "Any chance of me turning back into an octopus some day?"

"We have no reason to believe that." Okuda reached for a stick of pocky. "Your body had clearly been returned to the state in was in pre-octopus. So you'll just age normally from here on out. At least, that's what we have reason to believe, Takebayashi and I. And you're not unkillable anymore."

"I'm actually glad to hear it. I don't want my students to get old without me. And I'm even happier to see that the RH slither blood thing that you two figured out from what I left you worked out so well." He looked over to the Nobel Prize on the table. "It suits you well."

"I'm flattered. "Okuda laughed. "What about you? How's the next book coming along?"

Her teacher grinned. "Well you see, I've got the most wonderful idea..."

Koro-sensei realized it was time to write his magnum opus. The book he had been planning on writing for years, but wanted to hold off on until his newest blade- writing- was as sharp as could be. But he had written ten bestselling books of many different genres, all of which garnered international acclaim. He was ready for this, he kept telling himself as he put the pen to the paper.

Assassination Classrooom. A novel that posed as a work of "historical fiction" about that fateful year in a desolate classroom on an abandoned mountainside somewhere near Tokyo. Its author claimed it as a fictionalization, but promised to have interviewed the students who got caught up in the brouhaha. The last part was true, as Koro-sensei had made it a point to talk to each and every student to get an idea of what their feelings as thoughts were that whole year. He switched narrators and wrote from the perspective of every student, to get the most complete sense of what had happened. It ended up being seven thousand pages. The publisher wanted to either publish it in multiple volumes or edit it down, but "Kogoro Senuma" refused. "Everything I wrote is important." He insisted.

"Including the chapter about 'Miss Hellabitch's' boobs being so damn big!?" His literary agent was exasperated.

"Well you see, the students all agreed they were so damn distracting..."

E Class all sat down in the old classroom, in their old seats (though a few such as Karma couldn't fit in them anymore). It was storytime for the little ones, who were all brought.

Koro-sensei stood at the front of the room. "Okay, class. And kids. Open up to page one..."

Prologue

At one time, many years ago, the moon was bright and full and huge. You may already know this, and if you are old enough, you may even remember this time. That all changed on a bright cold day. March 13, 2015. That was the last day the moon as we knew it then, existed. Seventy percent of it was evaporated. Well, not evaporated. Shattered would be a better word. The moon was now a crescent and the chunks that were blown away floated around it, pulled in by the moon's gravity. The world just collectively stopped functioning for about a week. What happened? How could this be? The media lied. It was a meteor that went straight through the moon but somehow managed to not push it off of its orbital path, they alleged. And with that, the world went back to its normal thing. Dogs barked, children played, the sun rose again in the morning, and jeopardy still came on at eight. But the world leaders, and a select group of assassins, and lastly a special classroom full of students knew the truth.

There was no meteor. There was only an "alien" octopus upon whom the destruction of the moon was attributed to. Of course, that part was a lie as well. But what was true was that he was projected to explode and destroy the earth in a year. What else was true was that this octopus had a promise to fulfill to the woman he loved, the one who turned him into the teacher he became. So he accepted the blame, and negotiated with the Government of Japan to fulfill that promise. And only a few days later, he walked into the classroom of Class 3-E of Kunugigaoka Junior High.

"Nice to meet you. I'm the one who disintegrated part of your moon. And next year at about this time I'm going to do the same thing to the Earth. Also, I'm your new homeroom teacher. I hope we get along."

A shooting star shot by, again. This time, it was noticed by all.