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Kuroda Family Home
Grandfather, Kuroda Ryuichiro
Season 1 Episode 1
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 Teacher.
When she was younger, Yamaguchi was bullied because she had connections to the Yakuza. Instead of relying on the family name, she asked Kyotaro Oshima to teach her to fight and defend herself. The reason why she became a teacher is because of Minoru Tatsukawa's incident when she was a first year in high school. The members of Kuroda Clan respects Kumiko.
Kumiko looks weak but she is very skilled at fighting. Its shows at the First Episode that she dodges the Pachinko threw by her student but, she pretended that she was so surprised that she really did it.
Kumiko has been portraited having a black hair tied in a pigtails. She is mostly seen wearing jumpsuits or tracksuits. She is always seen wearing her glasses minus the one time she dressed up and had her make up done for the meeting with the other yakuza leaders.
Kumiko and her grandfather have a typical grandfather-granddaughter relationship. And like any granddaughter, she worries about his health and tends to keep things from him; to avoid adding stress on him. From what's known, since his daughter's death, he's very protective of his granddaughter and isn't afraid to use his status against those he think will harm her. There have been very rare times he's ever gotten angry with his granddaughter, for the most part he tries to give her space and accepts her for what the path that she wants as a teacher.