Hello everyone! Welcome to the first chapter. I've been playing around with the idea of a fanfic where Issei has a younger sibling for a while now, and this is the end result I've decided to go with. I hope you all enjoy it!

Chapter 1:

Date of Death

(Hyoudo residence):

A teenage girl washed her face as she prepared for the day ahead. She had an even peach skin tone, straight brown hair that reached the middle of her back and large doe brown eyes. Her slim figure provided an athletic appearance.

Exiting the bathroom she caught sight of a boy who looked slightly older than her, with hair and eyes matching her own in colour. He was giving her a warm smile.

"Hey Yukina," Issei greeted his younger sister. "Ready for your first day at Kuoh Academy?"

"Yeah," the girl, now identified as Yukina Hyoudo, replied. The pair began walking downstairs to join their parents and have breakfast. Yukina was a year younger than Issei and had successfully been accepted into her brother's school as a first year transfer student.

"I'm sure you'll love it there," Issei assured. "I can already see you getting along with everyone else. Still, if anyone gives you a hard time, just let me know okay?"

"Thanks Onii-chan, I will." Seeing her brother about to say something, she predicted what it was and spoke ahead. "Don't worry, I won't call you that in public. I'll use 'Onii-san' when around others."

"Thanks," he sighed. "I'm not exactly the most popular of people around school, and I have a feeling that some absurd rumour would take off if you called me that in front of everyone."

"Okay." While she knew her elder brother was somewhat perverted, he was essentially a kind person and she didn't want to cause any trouble for him. Still, it would be nice if he learned to reign in his hormones more.

(Kuoh Academy entrance gate):

The two siblings approached the former all-girls school together, walking side by side but with Issei slightly leading. Almost predictably, the majority of students around them who noticed the pair began whispering amongst themselves whilst also being shocked that a rather cute girl would be willing to walk next to Issei of all people.

Ignoring the whispers, stares and in Issei's case glares, the two Hyoudos continued walking onto the school grounds. When they reached the main building, Issei guided Yukina over to the faculty office so that she could receive her timetable.

"Well, here we are," Issei told her. "I'm sure you'll have a lot of fun in this place. Besides, like I said before just let me know if anyone gives you a hard time and I'll deal with them."

"Thanks Onii-san," replied Yukina. "I'll see you at lunchtime. I'll be waiting at the main building entrance."

"Alright, we'll eat and then I'll show you around the campus." With that, brother and sister parted ways.

(Issei's classroom):

The moment that Issei walked into the room, he was approached by his two friends Matsuda and Motohama, both looking on the verge of tears.

"How could you do this to us Issei?!" demanded Motohama whilst grabbing the teen's shirt.

Issei could guess what he was referring to, but just to be safe he asked anyway. "What are you talking about man?"

"We demand an explanation!" Matsuda declared, tears of betrayal streaming from his eyes. "How is it possible that you walked into school today with a cute girl next to you?!" At this point, pretty much everyone in the class was watching on, also curious as to who the girl Issei arrived with was.

"Dude, calm down already," Issei placated, calmly removing the offending hands from his shirt. "That was only my younger sister, she got accepted into this place as a transfer student."

"S-sister?! How could this be? Why have you never mentioned anything about this before?!" the bespectacled teen demanded.

"Well, what need was there?" Issei replied. "Plus, you guys never asked. Oh yeah, you two might be my friends and all, but please lay off her. You'll only get turned down, and I'm gonna get ticked off."

"Damn it Issei," the ex-jock breathed. "Fine, your sis' is off-limits. Besides, bro' code and all man."

Issei smirked. "Thanks."

Soon after, the teacher came in and the class settled down, although the whispering persisted.

(Main Building entrance):

After the lunch bell rang and class had been dismissed, Issei had grabbed his bento and made his way to the agreed meeting point. Yukina was already waiting for him.

"Come on, let's go to somewhere less crowded and eat," Issei suggested upon reaching her. It would also help to get away from all the stares and whispers.

Once they were finished with their lunch, Issei started guiding his sister around the campus while discussing how she was finding Kuoh Academy. It seemed that she was already on good terms with the unofficial school mascot, Koneko Toujo. Eventually, they reached the forlorn looking old school building.

"What is this place?" Yukina asked curiously.

"This is the old school building," Issei explained. "Nobody really comes here anymore besides the Occult Research Club, since this is where their clubroom is."

The younger Hyoudo's eyebrows perked in recognition. "Oh, I think that's the club Koneko-san is in."

Issei smirked. "Yeah. Pretty much the most popular students of this academy are in that club."

Suddenly, the wooden window opened and the pair caught sight of a beautiful redhead girl with emerald eyes and a buxom figure. Her gaze met theirs for a few seconds, her eyes unreadable, before she retreated back into the building and out of sight.

"Pretty," murmured Yukina. "Hey, Onii-san, who was that?"

His oculars still lingering on the now vacant open window, Issei replied. "From what I've heard, that's Rias Gremory. She's a third year and considered the most popular and beautiful girl here at the academy." Any further conversation was brought to an end by the ringing of the bell, signalling that it was time to get back to class.

(Hyoudo residence):

Issei and Yukina returned home when school finished for the day, knowing that their parents would be eager to hear about Yukina's first day. They had both been so happy at their beloved daughter being accepted into the prestigious institute.

There had been a slight incident earlier, where the pair had stumbled upon a teenage girl from another school about to be mugged by a group of five thuggish guys. Issei had at first politely asked them to leave the girl alone, but the brutes ignored and then threatened him. When two of them began advancing on Issei with raised fists, Yukina stepped in and both siblings proceeded to give a good beat down to the punks. A few years prior, their parents had insisted on them taking a few self-defence classes involving basic MMA, though both siblings adapted it into their own method of freestyle brawling. The girl had thanked them sincerely and called the police as they walked away and continued homeward.

They finally reached the door of their house, waiting patiently after Issei rang the doorbell. However, neither of them had noticed that during the entire journey from the school gates till now, a petite white-haired girl had been observing them from a distance. When the door opened and the parents welcomed their children inside, she turned around and walked away.

"Yukina, how as your first day?" their mother asked happily yet expectantly.

"It was great," the brown-haired girl told her. "Everyone was really friendly." She giggled briefly. "A few people said that they felt sorry for me because I have to live in the same house as Onii-chan." Issei for his part gave an offended scoff.

"I'm not that depraved," he muttered in an annoyed tone.

After a few more minutes of Yukina telling their parents about her day, each member of the family went to do their own things. When dinner had been made and everyone ate, the two teens decided to call it a day and go to sleep.

(Next Day: Kuoh Academy):

The siblings bade each other farewell as they parted ways to their respective classrooms. The fact that Issei Hyodou, infamously irredeemable pervert, had a cute younger sister was still the hot topic of the school. Issei gave a small sigh. He hoped that nobody would bother him regarding her, but he felt as though that was simply wishful thinking.

(Lunch break: Issei's classroom):

Issei grabbed a hold of his homemade bento as he prepared to depart from his desk. Suddenly, a pair of hands slammed down onto the wooden surface. A curious expression on his face, he looked up to see none other than Murayama, a member of the kendo club and one of his regular punishers. Her face showed that she didn't want to be anywhere near him, but at the same time she had something important to discuss.

"What do you want?" he asked neutrally. "And for the record, I haven't done anything to warrant a beating yet."

"I'm only going to say this once Hyodou," she stated seriously. "Don't you dare try using your sister to get away scot-free from any of your perverted antics. And don't you dare try to corrupt her either, otherwise I swear I will kill you myself."

The brown-haired boy's eyes half closed in an 'are you serious?' look. "I'm not that low, I do have morals and standards you know."

Murayama stared at him piercingly. "You better make sure." Without wasting a moment further, she turned around and hastily retreated, as though he carried some kind of plague.

"Geez, what's her problem?" Issei grumbled.

(After school: Elsewhere in Kuoh):

The Hyodou siblings were on their way home. It seemed that Yukina had become quite the popular figure. Issei was happy for her, but wished that people would get off his case already about not using her as leverage or somehow corrupting her through his perversion.

"Um, excuse me!" a voice suddenly called out. They turned to see an attractive girl around Issei's age, with long black hair and violet eyes. She was garbed in the uniform of another school.

"Yes, can we help you?" asked Yukina.

The girl began fidgeting and a slight tint manifested on her cheeks. "Um, are you Issei Hyodou?"

"Me? Yeah I am," Issei told her. "Why?"

"Are you seeing anyone right now?" the mystery girl inquired. "As in romantically?"

"Eh? No, I can't really say that I am," said Issei whilst scratching the back of his head. His younger sister was staring at the girl in disbelief mixed with some slight suspicion.

The girl's blush darkened. "Please go out with me!"

Issei's brain shut down for a few moments before it rebooted and her words registered. He looked at her in utter amazement, his mouth hanging open like a fish. On the other hand, Yukina's brow furrowed into a light scowl as she regarded the girl.

"And why would you suddenly request something like that when you barely know him?" the younger Hyodou interrogated. "No offence to him, but my elder brother isn't exactly the most chivalrous of guys, so why are you doing this?" She ignored an annoyed "Hey!" from Issei.

The raven-haired girl twiddled her thumbs nervously. "Well, I've seen him whilst walking around quite a few times and he seems like a nice, considerate person. He tries helping people as best as he can when he sees them having a problem. I saw both of you yesterday too, when you saved that girl from being mugged or worse. That's why… I was hoping that you might… you know… be willing to go on a date?"

"Sure!" agreed Issei whilst flashing a wide, toothy smile. He grabbed his sister's shoulders before she could protest and turned her around along with himself. "Come on Yukina, please give her a chance," he whispered beggingly. "This could be my big break."

Yukina sighed, briefly glancing over her shoulder at the other female. "Well, she seems legit I guess. I just hope that she's a good person. Ah what the heck, it's your choice Onii-san, do whatever you want."

"Thanks!" Issei released his arm from his sister's shoulders and turned back around. "Like I said before, sure, I'll go out with you. She's okay with it too, so don't worry."

The girl's face lit up and she smiled happily. "Really? Thank you! Oh, I'm so sorry, I forgot to tell you my name. I'm called Yuma Amano. We should trade numbers. Um, is Sunday alright with you?"

"That sound like a good idea," Issei agreed, taking out his phone. "And yeah, Sunday's fine. Does one in the afternoon sound good?"

"I'll be there!"

Standing at the side, Yukina couldn't help a small smile forming on her face. Her brother seemed so genuinely happy. Yuma and Issei finalised other details for where to meet up and such.

Once the pair arrived home, Issei told their parents the glorious news of him finally getting a girlfriend. Needless to say, they were overjoyed and started crying tears of joy and relief. Issei was a little put-off when they absent mindedly remarked about how their "hopelessly perverted son" had at last found a girl "willing to put up with him". Yukina giggled at the comedy of it all and wished her brother the best. Truth be told, she wouldn't mind having a big sister figure and Yuma appeared nice enough.

(Sunday: Outside the train station):

Issei gulped as he adjusted the collar of his light grey blazer. Today was his big day, his first real day. Of course, Matsuda and Motohama had been anguished when he broke the news to them. They had cried tears of fury and lament, cursing Issei and calling him a traitor all the while. A little while ago, some chick in a weird bat cosplay handed him a flier with a magic circle design on it. The text claimed that it would 'fulfil his wish!'. He stuffed it into his pocket absent mindedly.

"Issei-kun!" called a voice. The teen looked to see his date approaching him. She was wearing a long white dress with a contrasting small black coat, left open. Simple but endearing. "Sorry, were you waiting for long?"

"No, it's fine, I only came here a bit ago," he assured. 'Alright, I've always wanted to say a line like that!' he mentally cheered.

The two spent the rest of the day going out to various places, like the arcade and café, and having an enjoyable time together. It turned out that Yuma was actually quite good at the dancing game, to the point where she set a new high score. Issei even took care not to let his less savoury side get too out of control. All in all, everything seemed to be going along just fine.

(Night time: The Park):

The young couple walked together towards the fountain, both sporting small smiles. Issei and Yuma were pretty much alone, nobody else being around in sight. However, it just so happened that Yukina was taking a walk of her own through the small pocket of nature, only that they hadn't seen or noticed her.

"Yuma, I had a lot of fun with you today," Issei told her. "Thanks a lot."

"No, I should be thanking you," Yuma gently rebutted. "You're a really nice guy and considerate too." She raised her wrist and looked fondly at the scrunchie-like accessory adorning it. "Not to mention you give some cute gifts."

The brown-haired boy chuckled.

Yukina caught sight of her brother and his date, but kept her distance.

"Wow, what were the odds of me being in the same place as Onii-chan and Yuma-san at this time," she murmured to herself. "I should give them their privacy."

Issei turned to face the raven-haired girl accompanying him, the fountain's edge right behind him. "Hey Yuma, can you close your eyes for a moment?" he requested. "There's a little surprise I want to give you."

She looked at him in confusion for a moment, but complied nonetheless. "Alright."

Issei fished something out of his pocket and then carefully clasped it behind Yuma's nape with both hands. "Here, you can look now," he prompted. She did so and gave a slight gasp of surprise.

Hanging from her neck on a beautiful silver chain was a necklace consisting of a light purple gem with silver angelic wings on either side. It looked fairly expensive and well made.

"I hope you like it," Issei said nervously. "Dad helped me pay for that. I wanted to get you something good since you're the first girl I've actually ever gone on a date with. Like Yukina mentioned when we first met, I'm not exactly the most noble of guys, and I'm not really that good-looking either, but you still asked me out. It made me really happy, so I kind of wanted to make you happy too." He focused on Yuma. She appeared to have tears forming in the corners of her eyes. "Hey, are you alright?" he asked in concern.

He wasn't able to say anything further because Yuma suddenly flung both of her arms around his shoulders and pressed her lips to his. Issei's brain stopped then shut down out of shock. From her observation point, Yukina blushed and looked away, not wanting to somehow intrude upon the tender and most likely private display. When Issei finally regained use of his mental faculties, Yuma had already pulled away. She was smiling at him happily.

"Thank you Issei," she said warmly. "It's wonderful and I love it."

Issei managed to give her a gentle smile of his own. "So, does that mean you wouldn't mind going on another date with me?"

"I'd like that a lot," Yuma replied.

"It'll never work," a cruel voice unexpectedly spoke out.

The next thing Issei knew, he'd been stabbed through the gut by what looked like some kind of spear made from light. The weapon suddenly vanished and his body began to fall, blood already leaking out of the gaping hole profusely.

"Issei-kun!" Yuma screamed as she caught his falling form and held him in her lap. She looked at him with terror in her violet eyes. "No! Please, don't die! Please!"

Even though she didn't fully understand what had just happened, Yukina's body acted of its own accord and she found herself rushing forward. "Onii-chan!" she screamed in horrified concern.

Yuma's head whipped around in her direction. "No, stay back!" she warned. It was too late. Just as she neared them, another spear appeared and impaled Yukina the same as her brother had been moments ago. She too fell down with a bleeding wound in her abdomen, landing on Issei's chest.

"It would never have worked out anyway. He holds a dangerous sacred gear within him," said the cruel voice. "I don't know why you even bothered with this foolishness Yuma."

Yuma turned back to see what looked like an older and more mature version of herself, only with a sadistic facial expression, a pair of black feathery wings and little to no clothing. "Why are you doing this?!" she screamed, tears of anguish and anger spilling from her eyes.

"You'd never understand," scoffed the winged woman. "Nothing against you personally Yuma, but I'm afraid I can't just leave you in case you run off and rat me out, little sister." Before Yuma could retaliate, she was roughly grabbed and restrained. She was then taken away as the fallen angel took to the air, shouting in protest all the while no matter how futile it was.

Issei lay motionless on the ground, his younger sibling lying on top of him. Both were bleeding out copiously. Despite the burning agony, the brown-haired boy had still been able to process everything he saw and heard.

'What the hell just happened?' he thought, his mind desperately trying to stay conscious. 'Who was that woman? What did she mean by sacred gear? Why did she stab me and where's she taking Yuma? More importantly, how badly hurt is Yukina?'

"Onii-chan, it hurts," Yukina whimpered. "It hurts so much… and the blood won't stop coming out… It feels so cold… Please, help me Onii-chan. I'm scared."

'Damnit!' Issei screamed mentally, unable to do anything besides wrap one arm around her body after exerting great effort. She fell unconscious, although her brother couldn't tell. 'Please, if there's anybody there, save my baby sister. I don't care who you are, whether you laugh at me or even spit at me.' Unbeknownst to him, the flier in his pocket started to glow crimson. 'You can even leave me to die, but please save Yukina!'

The flier shined brightly before the light rapidly faded and a female figure appeared. Issei vaguely registered their blurry outline before the darkness completely encroached his vision.

"My, what an unexpected situation," remarked the new arrival. Her most prominent feature was her long crimson hair. "Well, since both of you are on the verge of death, I think I'll revive you as members of my peerage." Rias knelt down and gently moved Yukina off Issei. "Your condition seems more severe, so I'll start with you," she murmured to him. "Looks like only my pawn pieces will be sufficient."

Rias retrieved eight glowing crimson chess pieces, more specifically pawn pieces. She laid them down on Issei's chest. However, before she could begin the reincarnation process, she felt as though something was blocking it, or trying to reject the pieces. Not willing to give up, or lose the chance to save the siblings and add them to her group, she tried harder. The rejection rose to match her efforts. Rias frowned in frustration as she pressed on.

The evil pieces started vibrating. Soon, they were shaking wildly and erratically. Without warning, they all shot off Issei's body and floated above his prone form, circling around in mid-air. The Gremory heiress observed in shock, not understanding what was occurring nor knowing how to stop it. The eight pawns rotated faster and faster. Three of them suddenly glowed before two of them streaked into Yukina's nearby body. The remaining one along with the other pieces dove into Issei's chest and entered him. A moment after, both teens were completely healed and perfectly whole.

"I don't believe it," Rias breathed, staring agape at the pair. "Those three pawns felt like mutation pieces. But how could he force the evil pieces to mutate, especially when he's not even awake?" Nonetheless, her lips morphed into a smile yet genuine smile. "It seems that the two of you are truly something special. I can hardly wait."

What did you guys think? Please review/comment. I'm open to constructive criticism, but please don't flame. Also, I want to make one thing very clear from right now: I do NOT make incest pairings. I find them creepy as heck, so don't ask for Yukina to be paired with Issei. I already have a separate pairing for her, but it won't happen for quite a long while.