Warning! This story contain spoilers for Koro-Sensei's past!
(A/N; Completely random AU were Nagisa is the God of death (IE Koro-Sensei)'s apprentice, and the two of them go to a school as part of a assassination job, where they meet the rest of the cast.
The job was simple enough. Sneak in, kill the target and his wife, then slip away into the night.
It was his first time in Japan, but he picked up the language as easily as he always did. It was a pretty low-grade job, killing some unknown politician, but the pay was good and he needed the money, so why not?
Shinobu Koro (which what he was actually called, but was his name according to the forged driving license in his pocket) sat outside his target's house completely hidden in the overgrown bushes.
The house was average size (at least for Japan, compared to the houses in the slums it was a mansion) it was clearly well looked after- The paint looked immaculate without any chips, the car didn't even have a hint of dirt on it, and the flowers all bloomed beautifully. It was a pity this family wasted so much time on making their house look presentable when they'd be dead soon.
"Nagisa! Why are you always causing trouble for me?" A muffled voice female shrieked from somewhere. Trouble in paradise? Koro thought, slightly amused. The next sound left him less amused;
The harsh sound of a slap then the thud of a small body hitting the ground.
The assassin narrowed his eyes; He was almost entirely desensitized to violence, after all, were he'd grown up a day didn't go by without it. It wasn't uncommon to see children have their legs broken by corrupt police officers, or to be drugged up and used by gangsters.
But that didn't stop Koro from finding child-abuse distasteful.
"Why can't you do what I say? Why do you have to be so stupid?" The shrill voice was fading now, getting harder to hear. Oh well, she'd be dead soon anyway.
It was another hour before Koro made his move- After he'd scanned the area and made a thorough note of the layout and security systems, he went in.
The burglar alarm was simple to dismantle, and the locks were almost too easy to pick. The assassin was in the house within seconds.
The inside was exactly as he imagined; immaculately clean with bland decor. Without making a single sound, the assassin crept through the house, just by listening to the smallest of details, he could tell that the target was in the study and his wife was in their bedroom.
The assassin went into the kitchen, and took one of the families own knives before going upstairs.
He went for the wife first. She was sat in front of the mirror brushing her dark blue hair. She was a very beautiful woman, but there was something about the look in her eyes that made her seem harsh.
Silently, before she had a chance to even notice him, Koro had entered the room and snuck behind the woman, and slit her throat.
Her navy blue eyes widened in horror, and her hands grasped at her throat that was now flowing with crimson red blood. She tried to cry for help, but only a gasping, chocking sound came out of her mouth.
"Poor thing." Koro said, his tone convincingly sympathetic (although the look in his pitch black eyes was remorseless). "You don't even realise your about to die until it's too late."
The woman tried to turn to face him, her face was ashen white and her eyes bulging- she was no longer pretty- but instead she slipped backwards of her stool and hit the ground, hardly conscious.
"I bet you can feel the blood pulsing out of you right now.. But pretty soon that pulse is going to feel fainter and fainter." The assassin said, matter-of-factly. Death was a way of life for him, it always had been- the one sure, constant thing you could relay on in life, was death.
People die when you kill them.
The other person dies so you get to live.
Finally, the woman lay still on top of the carpet soaked with her own blood- not so immaculate now, is it -Koro thought nastily. Then, as he predicted, his target came running into the room, hearing the noise.
"Hiromi?" Mr Shiota called out, as he ran in. "Are you all ri- "
He was cut off as the assassin waiting behind the door sprang at him from behind, forcing the knife into Shiota's hand, then pulling his arm up, causing him to cut his own neck with the knife still soaked with his wife's blood.
Shiota dropped to the floor. Inches from were his wife lay, the knife still held loosely between his fingers. He twitched a few timed before lying still.
The assassin observed his handiwork- A textbook murder-suicide scene, he thought passively. Just what his client had ordered.
Koro turned to leave, ready to collect the other half of his pay, when suddenly, he noticed a small blue-haired child standing in the doorway.
"You killed Mummy and Daddy." He said matter of factley
Ah- this was where things got complicated.
"You made it look as though Daddy killed Mummy." The kid accused, although there was neither anger nor fear in his voice. For a kid that couldn't be older than six he was remarkably perceptive, and terrifyingly calm. "Are you going to kill me now too?"
"Sorry, kid, can't have any witnesses." Koro told him, the child's eyes widened. The black haired man had never killed a child before.
"Don't!" He said suddenly. "I wont tell. ..So take me with you. And teach me how to be strong like you are."
The assassin cocked his head- What was with children wanting to become his apprentice after they witness him killing their parents? He already had one protege who had come to follow him in the same way.
"Fine- it's Nagisa, right?." Koro finally decided; He liked this kids perceptiveness, his first apprentice was already a big success and plus, he didn't particularly want to murder a child. So this was the logical choice. "But once you're in there's no turning back. Death might be easier."
The assassin held out his hand, and the boy took it.
"What's your name?" Nagisa asked. Koro smiled in that disarmingly dazzling way of his.
"You can call me the God of death."
9 yrs later.
"How do you feel about a deep-cover year-long assassination mission?" The God of death asked (although the black haired man's current alias was Cole). Nagisa looked at him with calm blue eyes.
"I think I don't have a choice either way." He said with a slight groan, as he cleaned the blood of his knife in the motel sink. "You've been taking on some weird missions lately, ever since your first apprentice betrayed you and you were almost captured."
"But you'll follow me anyway!" Cole said brightly, but Nagisa didn't miss the way his eyes narrowed slightly at the mention of the betrayal. The God of death still couldn't work out how he had allowed that to happen.
"Unfortunately." The teenager sighed. "So- what are the details?"
"Elite boarding school, string of unfortunate deaths there- The authorities rules them accidents, our client knows better. We're going to find the killers" The master assassin explained.
"We're assassins, not detectives ." Nagisa commented dryly.
"Of course, our client wants us to kill the murderer once we work out who it is. We'll be going in deep-cover" Cole said, smiling. "Besides... It's in Japan."
The blue haired boy perked up at that, looking away from the sink to meet his master's eyes.
"That got your attention." Cole said, triumphantly. "You haven't been to your country or origin for a while, have you? Well.. This'll be your chance to finally attend school there. Who knows? You might even make some friends!"
(A/N: Sorry this is so short, weird and confusing! Please leave reviews to tell me if I should continue or not :p