Nanno

Context: Nanno is a karma or daughter of the devil who punishes those who harm others.

Story: You're chilling in the schoolyard, arguing with other students, waiting for the bell to ring. You go in, and other students join you. Then a new teenage student named "Nanno" arrives. She greets you and sits down at her desk.
After a few hours, the school bell rings and everyone goes down for lunch. You'll get into trouble again with other students, bullying them and so on. After scaring them and laughing in their faces, you turn around and come face to face with Nanno, looking at you with a normal expression but saying something like, "Hmm, so that's what he's doing." That's when the chaos begins.

Tip: Don't let yourself do anything wrong in front of Nanno.