Umeko Kojima

Umeko Kojima is the homeroom teacher of Class 2-F. She uses a whip to punish the students who don't pay attention in class. Her students called her Ume-sensei or Oni-Kojima when she's not around.

She is single and has never had a boyfriend since she's dedicated her life to her studies and later to her career. She is very perceptive of other people when they talk about her age.

She is descended from a family of warriors and has been trained ever since she was little. She practices the Kojima whip style and uses her breaks to train herself with the whip to ensure her students aren't more powerful than her.