Refusing to abandon her "precious students," Kumiko takes to the streets. She eventually discovers that Ren was framed by a powerful mastermind. The story culminates in a massive showdown where Kumiko must protect her past and present students from a threat far more dangerous than simple street gangs.

Ryu Odagiri (Kazuya Kamenashi), one of Yankumi’s original students from Season 2, returns to her school as a student-teacher.