Disclaimer: Majin Tantei Nougami Neuro and Assassination Classroom are both manga by Matsui Yuusei, who is more awesome than I.

A/N: I wrote this a while ago, back when only 11 chapters had been released and I had read only about four of them, and that's the reason why some characters and concepts aren't in here. There's definite scope for a continuation, so I might write more, but for now, I'm marking it as complete. Complete 'n' cracky, mind you.

It's my entry for these two fandoms for the 5, 10, 20, 50, 70, 100 Fandoms Challenge at the Harry Potter Fanfiction Challenges Forum and also for 100fandomhell at livejournal.

I hope you'll enjoy it! :)

Assassination [Case File]

It wasn't so far into the school term that Yako and Neuro moved their Demon Detective Agency and entered Kunugigaoka Junior High School. Despite their fame and – hang on, aren't they too old? – well, despite that, there were few ripples outside of the school itself – that, and a few government officials, those who were suspicious of the detectives' motives, those who knew the truth about Koro-sensei of Class 3-E… But they kept things low-key and quiet, only watching closely, not interfering until they knew whether their decision to enter the school had anything to do with 3-E or not.

It wasn't so far into the term that Yako and Neuro got themselves transferred to that very same class, either. With Yako's bad grades and the way Neuro had of throwing her at walls, windows, teachers, other pupils and visiting dignitaries, it didn't take long for these famous figures to be quietly shunted to one side. To the End Class. Newspapers exaggerated things, didn't they? Katsuragi couldn't be as skilled as they'd heard.

Even the government officials relaxed for a moment, too. If she and her assistant were really like this, the risks of them being in class 3-E were lower than they'd thought…

And as for class 3-E themselves? They figured otherwise pretty quickly, when Nougami became BFFs with Karma and the notorious criminal Aya Ajia wandered in to have a friendly chat with Katsuragi that one time, but then, class 3-E were hardly normal themselves.

They were the Assassination Class. And they had a job to do. These newcomers, strange as they were, could possibly help them save the world.

Six minutes and fifty-three seconds into her term there, Yako ducked away from another uprooted tree as it flew past, panting in fear. 'Neuro, did you have to duke it out with Koro-sensei near all the students?'

Ha. Of course he did.

In her distraction, the next tree would have decapitated her if it weren't for a boy grabbing her by her wrist and pulling her out of the way.

"I'm Shiota Nagisa," he told her once they were further away.

"Katsuragi Yako," she said, and smiled.

Not long afterwards, when the two duellists had decided to call it a draw, Nagisa would have another weakness of Koro-sensei's listed in his notebook: 'Other supernatural beings.'

But that was okay. It was okay for Class 3-E to know about Neuro. They were hardly normal themselves.

Things were quieter today. Behind some trees, the students of Class 3-E hid, watching Koro-sensei and Nougami Neuro.

"What do you think they're doing?" whispered Kaede.

Nagisa's eyes narrowed slightly. "Well, those green stripes mean Koro-sensei is looking down on him…"

They stood there wordlessly, watching a green-striped Koro-sensei staring into the eyes of fellow student Nougami Neuro, who stood upside down on a tree branch high above him, literally… looking…

"…Are they having some kind of contest?!"

Koro-sensei was lying stretched out by a tree again this morning, sampling sweet foods and basking in the sunlight. He smelt his approaching students before he saw them. 'So…'

As they had once before, they ran towards him with large smiles on their faces, begging to try his food. 'Better smiles,' he rated, 'though still too fake. Though, that girl… Yako-chan…'

Yako was 100% enthusiastic. He couldn't distinguish this smile from her normal one.

'Impressive!'

…Or not.

"Hey!" yelled Terasaka when the feast was over. "You just wanted the food! You didn't even try to kill him!"

Katsuragi looked up from her licked-clean plate with innocence in her eyes. "Hm?" she asked absently – then… "Ooops! Oh no no no no no, I didn't mean to! I just got carried away! The food was just… such high quality!"

The other students scoffed, disappointed, as Koro-sensei began the usual 'improvements session' he gave anyone who failed to assassinate him.

The shine on Yako's hair afterwards was so intense that no one except Neuro and Koro-sensei could look at her for a while without going blind.

Nevertheless, for the first time, he failed to get the message across. Whenever Yako was involved in similar stunts in future, they were always failures, for the exact same reason.

And every time, Neuro would assume his stupid face and say, "Sensei is such a pig!"… never specifying which sensei he meant.

In fact, it had been obvious, early on, that Yako and food would be a problem. Simply put: Class 3-E, the isolated building in the middle of nowhere, had no kitchens.

.

.

.

Yep.

And if he wanted to be a good sensei for them all, Koro-sensei, despite his Mach 20 speed, couldn't keep taking trips to get her food during the school day, once the food she'd bought had run out – which was always quickly.

You see, if Koro-sensei moved at Mach 20, Katsuragi Yako ate at Mach 30. And she almost always had room for more.

As it happened, Yako would solve this problem herself – though her 'assistant', Neuro, would always deny that, and following his lead, so would she.

Class 3-E had never believed in zombies up until this point, but it soon became clear that they existed.

"We live to serve Yako-sama," droned one of their old classmates – one who'd always bullied those in 3-E – as he hefted a massive pot of delicious-smelling soup up the hill to their building. "We live to seerrvvve…"

Yes, Yako would solve this problem herself – though she and Neuro would always deny having anything to do with it; Neuro would just say "Sensei has some fans, doesn't she?"; Yako would look appropriately embarrassed but nod when he grabbed her head.

Any similarities between her zombie fans and people addicted to the Electronic Drug were dismissed, and her late-night calls to one police officer, Higuchi Yuuya, were just her… catching up with an old friend.

And though they knew it was a lie, who were Class 3-E to criticise? They were the Assassination Class, and they had a job to do. A job that was illegal, under normal circumstances…

And they were hardly normal themselves.

In the background, Karma directed the zombies to where they should place their soup.

Oh, the knife? Well, no, he didn't technically have to use it, but…

Things were quieter today. Behind a few trees, the students of Class 3-E hid, watching Koro-sensei and Nougami Neuro.

Thanks to 777 Tools of the Demon World: Evil Board Game, they were playing Exploding Go. If a stone was captured, it would burrow into its player's skin and explode. Neuro was far more skilled, but Koro-sensei didn't seem bothered by the explosions, so as usual, things were looking as if they would end without any changes to the status quo.

"Your worms," said Neuro as they played, voice conveying a calmness that his ruler-straight back didn't. "You really care about their evolution, don't you?"

"Of course!" said Koro-sensei at once, nodding his head and grinning wider than usual. "Every sensei should."

"And you're successful, even with the lowest of the lowest pond scum that come to this class."

"Ah, thank you! That is a reassuring sentiment from a fussy species such as yourself! It's the carrot, not the stick, you know. Encouragement."

"The carrot, not the stick?" said Neuro. "Hmm."

Behind the trees, Yako listened, bug-eyed. She couldn't imagine Neuro using the carrot method… unless he did something unmentionably horrible with it, anyway…

The next day, even her best friend in class, Nagisa-kun, didn't remark on the red rings drawn around her neck in permanent marker. It fell to Karasuma-sensei to ask, concerned, why she had them, and for Karma-kun to remind her that neck tattoos make you more easily identifiable to the police ("Then again, they all already know you, don't they, Katsuragi? Hard luck for you!").

"Neuro was marking me," she mumbled, embarrassed.

No one said anything about them again – because hey, they were Class 3-E. They were the Assassination Class. They weren't exactly normal themselves.

And they had a job to do. Neuro and Yako, weirdo Piggish Detective and scary Demon With Strange Methods of Encouragement as they were, would help them save the world for sure.