Gokusen Season 2 (2005)

Sinopsis

Half a year has passed, and Shirokin Gakuen has closed down. Yamaguchi Kumiko finds herself a teacher of a few young kids, who don't really benefit much from her style of teaching. Through some twist of fate, she is offered a job as a teacher in Kurogin Gakuen. She becomes the teacher of a delinquent 3D class, which makes her previous students look like angels. In order to protect her job, she must again hide her true identity - the fact that she is the 4th generation of the Oedo Family, a prominent yakuza group. (Source: MyDramaList) ~~ Adapted from the manga “Gokusen” (ごくせん) by Morimoto Kozueko (森本梢子).