Assassination Classroom
So Karma is touch-starved (thanks to his parents).
They've never really cared much for him, and they've neglected him for practically his whole life (alert: that's another manifestation of abuse).
He doesn't remember when he's last felt touch from someone since he's practically been taking care of himself and raising himself for practically his whole life.
The fights he gets into are the only times he's ever been touched, and that's why he revels in them so much, why he loves them so much.
No one ever truly sees him, and he's so alone and he just wants someone's approval someone's love why-
Then he gets sent to 3-E.
Korosensei is constantly touching him, a tentacled finger against his forehead and a comb running through his hair, and he-
He loves it.
He gets so much affection and touches from 3-E.
He gets his first ever hug there too.
Karma feels absolutely elated.
He takes the opportunity to touch everyone in 3-E as much as he can.
A hand on their arm, an arm around someone's shoulder, he's not even ashamed with cuddling.
3-E secretly thinks it's kind of funny and adorable, but they're also happy Karma feels so comfortable around them.
A Class just sees the sadistic devil delinquent Karma cuddling up to someone in Class E and they're like what the fuck. They're positively freaking out.
3-E thinks it's hilarious.
The Main Campus is freaked out.
After that the idea goes blegh in a puddle of slop and laziness because there's nothing else.