Penguin's sister Kaede brings over some special made Daifuku to the student council. Unfortunately, it turns everyone except Kujira, who didn't eat one, into catgirls, who proceed to 'attack' the other students. This is due to a drug that Sebastian, the family butler, put in due to Penguin's request. Kaede uses her connections to capture all the cat-students, return them to normal, and send Penguin to the lecture room. The title is a parody of My Wife is a High School Girl.