The drug

Nagisa Shiota chose to become an assassin instead of a teacher. Now, he attends Teitan highschool while working as an assassin. He becomes close friends with Jimmy Kudo, and happens to tag along with him when Jimmy goes to the amusement park with Rachel. Nagisa is also turned into a child along with Jimmy. Nagisa and Jimmy grow closer as they both hunt down the syndicate. Nagisa as an assassin and Jimmy as an detective.
Warning: Boys love (Not a lemon) Suicide! Depression.