A new teacher, Yamaguchi Kumiko, came to Shirokin and as it turns out, she's the homeroom teacher of a class filled with delinquents who tried to scare her off. However, it's not going to be easy to scare off this teacher because she's actually from the Oedo family, a yakuza family, and her grandfather's the head of the family. Trouble arises when one of Yamaguchi's students, Kumai, is accused of stealing money from the school. As it turns out, he did and Yamaguchi's here to prevent Kumai from getting expelled. (thetvdb.com)