Akane Minagawa is a music teacher at Hanabi's school. She hides her true personality with a "mask" at the beginning of the story, but it's clear to see that she is very manipulative and takes pride in hurting others.

Spoiler

She is a compulsive cheater who would sleep with anyone to make her feel better about herself. She likes the feeling of being wanted and needed by someone. With that being said, both Mugi and Narumi fall in love with her, she doesn't mind playing with men and toying with their feelings.