Kumiko Yamaguchi

Kumiko Yamaguchi (山口 久美子 Yamaguchi Kumiko) is the main protagonist of the anime and manga series. She enters Shirokin High Private School to work as a math teacher. She was assigned as the Homeroom Teacher of 2-4, a class that has populated by many gang delinquents. But no one at school (apart from the principal) knows that Kumiko is the heir to the Kuroda family, a powerful Yakuza clan. She hides her background being a Yakuza to continue working as a teacher.