So I decided to make a crossover with one of my favorite mangas, Sekai Oni. Here it is!

Disclaimer: I don't own Naruto or Sekaioni

A six-year-old Naruto Uzumaki sat down in the office of Hiruzen Sarutobi. He had just visited after a mob threw rocks and trash at him. "Hey, jiji, can I help you clean up the desk? It looks messy." Sarutobi smiled and nodded.

One hour later, the desk was clean and the paperwork was put in its proper stacks. Naruto noticed an old dusty envelope partly under the desk. He picked it up and asked, "Hokage-jiji, what's in here?" He promptly opened it and crawled into the Hokage's lap. Sarutobi, equally confused, took the letter and read it out loud.

Dear Sarutobi,

If you're reading this, I guess you're Hokage again. It's me, Minato. I managed to make a deal with the Shinigami, so don't worry. Anyways, here's the explanation. I split up the Kyuubi's essence between my triplets Menma, Natsumi, and Naruto. I sealed the Kyuubi's Yang chakra into Menma and its Yin chakra into Natsumi. And the Kyuubi's soul was sealed into Naruto, as you already know. Menma and Natsumi need to train to use the Kyuubi's chakra, so I've taken them and Kushina out of the village. They need the training. Naruto will understand, I hope.

By the way, the village is treating Naruto great, right? I bet they're worshipping him like a hero for containing the Kyuubi's soul! I didn't want to leave him in the village, but it's for the greater good. Naruto needs to stay in the village for the prophecy to work.

Look, we'll be back when Naruto graduates from the academy and becomes a genin. I bet he'll be really happy to know that he has a family! Well, the Kyuubi is approaching, so this is the end of the letter, I guess.

-Minato Namikaze, Yondaime Hokage of Konoha.

At this point, Sarutobi was trembling in anger. The Sandaime Hokage had never felt such rage, not even when he found out that Orochimaru, his former student, was experimenting on children he kidnapped from around the village.

Naruto was trembling. "Jiji," he said, "why did they do it?" At this point, he was tearing up. He started bawling and cried, "I hate them! They left me because of a stupid guess about the future!" The aged Hokage merely patted the blonde on the back and whispered comforting words.

Come get me. I'm here. Naruto and Sarutobi's heads snapped up, looking for the source of the voice. Their eyes settled on a scroll on the Hoakge's desk. A scroll that wasn't there before. Young child, you have suffered much. I will help relieve your pain. Just sign your first name in the scroll with your blood. I swear I mean no harm.

Hesitatingly, Naruto grabbed the scroll and opened it. Looking to Sarutobi, who nodded nervously, the blonde bit his thumb and drew blood. "Naruto…" he mumbled as he wrote his name. Suddenly, the mirror in the room rippled as two eyes and a mouth appeared in it. The eyes looked like a multitude of ovals within each other, in a position that made it look almost hypnotic. The mouth was set in the shape of a large crescent Cheshire smile with sharp teeth.

Naruto and Sarutobi tensed, causing the smile to widen even more. "Relax," said the face. "I came here when you signed my name, Naruto. As promised, I will lessen your pain."

The blonde, wary, asked, "How?" Sarutobi mentally applauded Naruto's wariness and wished more children were more cautious.

The face said, "I have no name, but you may call me Egao. I was a citizen of a branching realm called Mirrorland, which was destroyed many years ago. As a result, I am forced to reside in reflective surfaces. I just got here from a lake in a forest somewhere in your village. I just want to finally join my family, but I want to help someone before I go."

The Hokage said, "Egao-san, please get to the point." Egao smiled and seemingly nodded.

Egao said, "Naruto, I will give you a summoning contract. It's for strong beings known as World Devils. A person will give you more information tonight in your mind. For now, finish your business and sign your last name before you leave."

Egao smiled and said, "Ah, now I can finally rest in peace and join my brethren…" The face began to disappear, but it suddenly returned. The spirit added, "Oh, and don't forget to take the scroll with you. That's the contract. Don't lose it." Egao faded once again, and then disappeared to the afterlife, reuniting with his family.

Naruto said, "Thank you, Egao-san." He opened the scroll and was about to write down his last name when he had a sudden thought. He turned to Sarutobi and asked, "Hokage-jiji, I want to change my last name. Can I have it changed?"

The Hokage nodded and took out a paper. "First, write your current last name here. Then write what you want your new last name to be here. I'll handle the rest," he said. The child nodded happily and started writing.

A few moments later, Sarutobi read what Naruto wrote. "So you want to change your last name to Sekaioni, huh? I guess you want to thank Egao-san for helping you." Naruto nodded, confirming his thoughts. Chuckling, the old man signed the form while Naruto wrote his new last name into the scroll, sealing the contract.

…

Naruto flopped onto his bed. "So I guess whoever Egao-san chose to help me will show up…" Seconds later, the six-year-old drifted into a deep sleep.

The blonde woke up in a sewer. Remembering what Egao said, he said, "Excuse me! Where are you?" A figure approached him, coming closer. Stepping into the light, Naruto saw a young girl who seemed to be around his age.

The girl had messy brown chin-length hair with a slight violet tint that covered the left side of her face. Her right eye was blood red, and if the boy could see her left eye, he would see it was a sickly shade of brown. The girl wore a black dress over a white shirt and black shoes.

She finally spoke and said, "I'm Azuma Shinonome. I guess I was chosen to teach you. Who're you?" The entire time she spoke, her face was emotionless and her voice was blunt. Naruto blinked in slight surprise.

Thinking quickly, he said, "My name's Naruto Uzu- I mean, Naruto Sekaioni. Nice to meet you, Azuma-chan!" Azuma nodded and started the explanation of the World Devils and Alices and their origins.

The next day, Naruto woke up and thought about what happened the previous night. "Man, who knew that Alices were fighters that could create weapons just by having knowledge about how they worked and thinking about them. Not to mention that World Devils are transformed Alices…" The young child looked outside and thought, 'Today my new life begins.'

…

Six Years Later

It was graduation day for Naruto. On this day, he would become a genin. It was also the day his biological family would come back. Naruto snorted. "Azuma and her friends are my real family," he muttered. He glanced in the mirror and reviewed how he looked.

Naruto had drastically changed in the past years. Despite being twelve, he was rather short at a height of 4'6". The blonde wore clothes similar to Azuma, except that a belt wrapped around his waist and instead of looking like a dress, there was a slit on each side of the cloth, making the clothing look like robes a certain snake would approve of. Also, he wore black shinobi pants. Naruto wore the standard shinobi sandals, also black.

Naruto's pale face was cute and flawless. Where were the whisker marks? The blonde lost them when he encountered the Kyuubi's soul and sent it back to hell with Azuma's help. Incidentally, the Kyuubi's soul was very weak after so long without chakra. Naruto's right eye had also become blood red like Azuma's.

The blonde's hair had grown out, giving him a feminine appearance due to his thin frame and androgynous/feminine clothing. Although it retained al small bit of its spikiness, the hair had mostly flattened out, creating a hairstyle almost exactly like Azuma's.

During his training with Azuma, Naruto had been improving his skills as a shinobi. He worked part time at the Torture and Interrogation Department, or T&I Department for short. He quickly made friends with the department's best interrogators, Ibiki Morino and Anko Mitarashi. They took him in as an apprentice, and soon he gained a reputation as the most terrifying interrogator, able to make prisoners confess in seconds. Sarutobi nearly had a heart attack when he learned about it.

Additionally, Naruto asked Might Guy, the village's best taijutsu master, for advice. The eccentric man was happy to do so, and the blonde quickly honed his taijutsu skill to the point he would make a chunin actually take him seriously. He also spent time meditating to improve his chakra control.

Snapping out of his thoughts about the past six years, Naruto went into the kitchen and made himself breakfast. He poured himself a glass of milk and made some toast. He was about to enjoy his meal when he glanced at the clock and saw that the academy would start in five minutes.

Naruto quickly gulped down the milk and dashed out the door. With the slice of toast in his mouth, Naruto ran towards the academy, not wanting to be late. He had overslept from training the previous night with Azuma, whom he had summoned into the real world. He ran into the classroom and quickly sat down in a random seat just as the bell rang.

Iruka Umino, the chunin in charge of the class, said, "Now then, let's begin the graduation test." As he said this, the academy rumbled as two certain girls ran towards the room.

Sakura Haruno and Ino Yamanaka dashed into the room at the same time and yelled, "First!" They both glared at each other and were about to fight when they noticed the seat they wanted was taken.

Naruto happened to be in that seat. "Hey idiot! Get out of my seat! I'm the only one who can sit next to my Sasuke-kun!" yelled Sakura. Ino was about to retort when Iruka snapped.

"GO SIT DOWN SOMEWHERE ELSE YOU BRATS! YOU'RE ALREADY LATE AS IT IS!" yelled the chunin, using his Demon Head Jutsu™. The two girls paled and sat down in random seats, still glaring at each other. "Well then," said Iruka, "time for the written test."

Naruto mentally snorted as the test given to him had a genjutsu over it. He secretly glanced at Mizuki Tojo, Iruka's assistant. The man smirked menacingly at him, unknowingly giving away that he was the one who placed the illusion. The blonde discreetly dispelled the technique and started the test.

Next was the weapon throwing section. Naruto watched his classmates try, with most of the civilian family students getting six out of ten at most for kunai and shuriken each. The Clan heirs scored higher at seven or eight each, but Ino and Hinata had the lowest scores at five and six respectively. "Watch how good I am, Sasuke-kun!" yelled Sakura as she threw the kunai and shuriken. Her respective scores were two and three.

Sasuke went up and threw the weapons. He received a perfect score for each. "Beat that, losers," he said to the class as he smugly walked back to join the others.

Finally, it was Naruto's turn. He calmly took the kunai and shuriken Mizuki provided and frowned. He asked, "Iruka-sensei, the kunai and shuriken feel strange in my hands. Can you check to see if anything's wrong with them?"

Iruka said, "Not at all. Let me see…" He weighed the weapons and frowned. "These kunai and shuriken are dull and greatly imbalanced. How did they end up in the class supply? Here Naruto, use mine." He handed new kunai and shuriken to blonde, who thanked him.

Naruto aimed and threw the kunai. He earned a perfect score. He threw the shuriken. Another perfect score. Iruka smiled at his favorite student's achievement while Mizuki, Sasuke, and the Sasuke fan club seethed in rage.

"Well then, it's time for the jutsu testing portion of the test," said Iruka, "I need you to do the transformation jutsu, substitution jutsu, and a clone jutsu. First up, Shino Aburame."

When Naruto went up, Iruka nodded at him, prompting the boy to start. First, Naruto transformed into Kaito Ookura, a friend of Azuma. Iruka and Mizuki were surprised when they saw Naruto transform into a tall bald man with two scars on his scalp. They were surprised even more when they saw the prison suit. Clearly, they didn't expect the boy to transform into a criminal.

"Good job, Naruto," said Iruka, "now do the substitution jutsu." The boy nodded and went up in a puff of smoke. When the smoke cleared, they saw an unusual sight.

The Sandaime Hokage was reading Icha Icha Paradise and giggling perversely. He mumbled, "Oh, Kuroki is such a naughty girl…" He suddenly snapped to attention and hid the book when Iruka coughed, a slight blush on his face. "Let me guess," said Sarutobi, "Naruto substituted with me." Iruka and Mizuki nodded, the latter grinding his teeth in frustration.

By the time Naruto returned, the only jutsu left was a clone jutsu. Naruto crossed his finger into a cross shape and said, "Shadow clone jutsu." Smoke filled the room as ten clones appeared. Wordlessly, Iruka handed Naruto a black headband, which Naruto took and replaced the belt with it.

The blonde knew the shadow clone jutsu because he had reported his trouble doing the clone jutsu to the Hokage. Sarutobi was shocked at Naruto's chakra levels and taught the technique to him. The next moment, Naruto mentioned using the shadow clones to speed up doing the paperwork. Sarutobi felt like an idiot afterwards.

…

Naruto dropped by the Hokage office. "Hey jiji, I passed," said Naruto. Sarutobi smiled and patted the blonde's head affectionately.

"Well, Naruto, do you know what day it is?" Naruto's aura became serious as he stood at attention and nodded. Over the past six years, the hate for his family disappeared and he let go of the anger at his parents, but Naruto was still upset about what they did. Maybe he would make them do things for him to make up for it…

Naruto snapped out of his thoughts when Sarutobi said, "Alright, I'll let them in now. You can come in now!" As he called out the last part, the door opened. In walked the Namikaze family in all its glory.

Minato and his wife Kushina looked just like they did in the village photos. They were quickly followed by two- no, three children.

First was Menma. He was the same age as Naruto and looked like a miniature version of Minato, but with red hair and violet eyes. He wore black pants, shimobi sandals, and a grey shirt. His aura radiated arrogance much more than Sasuke's did.

Next was Natsumi, Menma and Naruto's triplet sister. She was a miniature version of Kushina with blond hair. Her attire was the same as Menma's, but she also had a flak jacket. Although she did not radiate arrogance, she did have an air of cockiness about her.

Last but not least, Mito, the youngest sibling. She was six years old, and looked exactly like Kushina, but had sky blue eyes. She wore a plain yellow dress. The young girl held on to her mother's hand as she looked around the room in excitement.

Minato stepped up and said, "Hello, Sarutobi-sama. We're back. Oh, who's this kid?" As he said this, he looked at Naruto.

Sarutobi replied, "This is Naruto Se-" He was interrupted by Kushina, who quickly pulled the boy into a hug. When Naruto pulled himself out of her grip, the woman stared in shock. "As I was saying," repeated Sarutobi, "this is Naruto Sekaioni."

Minato and Kushina blinked in confusion. This wasn't their son? "But where's our son Naruto?" asked the former Hokage.

"I wasn't finished," Sarutobi retorted, slightly annoyed. "This is Naruto Sekaioni, formerly Naruto Uzumaki. He changed his name after we found the letter you left for me six years ago. In fact, Naruto was the one who found it under the desk. We read it together. He decided to change his name afterwards because he wanted to be seen as himself when you came back."

Minato and Kushina gaped in shock, and Menma decided to make himself known. "Heh, a loser like him doesn't even deserve to have our family name!" Sarutobi's eyes hardened and Minato and Kushina glared at Menma in anger Natsumi gave her brother a half-hearted glare, and Mito looked at Naruto in wonder.

The youngest girl ran up to him and excitedly asked, "Are you my other big brother?"

Naruto chuckled lightly and said, "Yeah, I guess I am." Minato and Kushina smiled at how their youngest daughter already made her way into the boy's heart. Meanwhile, Menma snorted in disgust and Natsumi raised an eyebrow.

The girl walked up to Naruto and said, "So you're the brother kaa-san and tou-san kept talking about, huh? Sorry, but you don't look like much." Naruto glanced at her and his lips twitched.

He said, "Looks are deceiving. I'm actually rather skilled. You'll see soon enough." Natsumi twitched slightly, but shook it off and smirked.

Menma huffed, "If Tou-san and Kaa-san left you in the village, it's clear that you're just a waste of space that doesn't deserve to be near us."

Immediately, he was hit by four people at once. Those four people were Kushina, Natsumi, Mito, and Naruto. Kushina growled, "Don't you dare talk about family that way!"

Natsumi said, "Stop being an idiot! I swear, you ego is nine times bigger than the Kyuubi itself!"

Mito cried, "Stop being a meanie to Naru-nii! He's your onii-chan too!"

Naruto stiffly said, "I already don't like you. I think you're more arrogant than the entire Uchiha clan, alive and deceased combined."

Suddenly, an ANBU burst into the room and yelled, "Hokage-sama! Chunin Miziki Tojo has stolen the Forbidden Scroll and is escaping with it!" He noticed Minato and his family. He started to scream, but fainted from shock.

Sarutobi said, "Naruto, this is your chance to show your family what you know. I'll handle the explanation to the ANBU. Minato, we'll have to announce your return to the village. For now, stop Mizuki!"

The shinobi in the room yelled, "Yes, Hokage-sama!" They then ran out of the room to apprehend a traitor.

Sarutobi sank into his chair and sighed, a large smile on his face. "Show me what you can do, Naruto-kun. I look forwards to your career as a shinobi." He then took out his pipe and lit it. The aged Hokage placed it in his mouth and looked out the window, anticipating what was to come.

And the first chapter is done! This is definitely the last time I'll be publishing/updating for a while, so I'd like to wish a good summer to everyone.

Please review, tell me what you think, constructive criticism appreciated, but no flames. Onishin Tsukitenshi, signing out.