The Snakes Place (Nagisa x Karma)

(Assassination classrooms not mine and the characters unless I say I made one up)
Nagisa is no normal kid as he claims to be. Karma knows something is different about Nagisa and somehow Nagisa doesn't even know it himself. Karma wants to find what is inside Nagisa and get it out because he wants Nagisa to be normal and his...

Short version

Nagisa is not normal and only karma can see. Karma wants to get rid of whatever is making Nagisa like this.