What would be awesome:

A super-strong, super-famous, almost-supernatural assassin from the past dies and gets reincarnated centuries into the future where the world is filled with future-modern (not so futuristic that there's jetpacks but not so modern that it's boring). There, he grows up in a low-class family but luck has it that he's quite intelligent, bit of an oddball due to his past life (he doesn't trust people due to being an assassin and is rather cold/tsundere) and very loyal. All through elementary school he pretty much is trying to fit in with the other kids, trying to learn the customs of the modern world, trying not to kill the snot-nosed brats, until one day he saves a girl from being kidnapped. It turns out this girl is quite well-to-do and immediately becomes very infatuated with him but she never learns his name or anything about him, but she's very possessive and unfortunately cannot have him because "humans aren't pets". Unknown to him though, she secretly swears that one day he will be hers and they split ways. He graduates from elementary school and goes into middle school. His parents inspire him to do better so he starts to do better and eventually does however he's extremely quiet, not cold but quiet and does not pay attention to people. He graduates from middle school. He goes to high school, a private high school that he was able to get into due to being such a genius as well as his kick-ass athletics in middle school and he gets scholarships because he's so poor. There he meets crazy yandere-otome-hime-sama from earlier however he's forgotten all about her and she tries all that she can to possess him, he doesn't know though, he's bad with people so he just treats her nicely which makes it worse. Eventually, she has him join a club with her, the mystery club. They love mystery novels, films, shows and even try to solve some of their own. He meets other quirky people who also weird. Eventually they come upon a conspiracy and he must fight the conspiracy, protect his new friends in the club and try to not be raped by the crazy girl.

Kind of like that. Slapstick/comedy/action/adventure/mystery

Please.