Under the threat of being disowned, Mafuyu Kurosaki—an ex-delinquent with a strong sense of justice, exceptional fighting skills, and a very dense head—has to start a new life as a proper citizen and student at Midorigaoka Academy. Apart from adapting to a new school, Mafuyu also has to get used to living alone as the dorms are full. Therefore, she starts a new chapter in her life with limited funds, the inability to make even a cup of instant noodles, and a big dream of becoming "an ultra-shiny female high school student."

This dream, however, is quite hard to fulfill since Mafuyu's sense of style is uncouth, and troubles tend to find her no matter how hard she tries to avoid them. The path to her dreams is made more difficult because of Takaomi Saeki, her unordinary homeroom teacher with barely legal teaching methods, and her delinquent classmate Kaori Hayasaka, who becomes her first new friend.

Oresama Teacher follows Mafuyu's adventure full of hilarious situations, ridiculous misunderstandings, and exciting action sequences, all while she still tries to become a normal feminine girl.