The all-boys Shirokin Gakuin High School has never had a female teacher, but now they are getting two; when the twenty-three-year-old Kumiko Yamaguchi is appointed as the new homeroom teacher of Class 3D, all the other teachers are aghast.

Kumiko is out on a mixer, when she happens to save Minami from a beat down; Shinohara and Kashiwagi go after the delinquents, but they failed to catch them.

After a series of purse snatching incidents occur near the school, the teachers wonder if anyone in Class 3D is the culprit; everyone doubts Uchiyama as he is behind on his tuition and his mother has been working two jobs to make ends meet.

Kumiko happens to learn about Shizuka's secret part-time job; Kumiko is worried sick, but Shizuka is confident no one will ever know.

Shin happens to learn Kumiko could be the next leader of the Oedo Family when he finds her lost cellphone; he observes Kumiko carefully as he decides what to do with her secret.

A competitive Kumiko is all fired up for the upcoming school sports competition; she puts together a game-winning plan, but most of her students could care less; Class 3D has no hope of winning since they do not have enough students to enter.