Aina Endou is a nice, cheerful, open-minded girl, but she can also be very direct. Even if you can’t tell by looking at her, she likes to rebel against the school rules and runs around with dishevelled hair, eats sweets at school that are actually banned, and casually addresses her teachers with nicknames. Amongst them is her homeroom teacher Tanaka, whom she always just calls “Tanakacchi.” Trying to talk some sense into her, he asks her to join him in the classroom after school. Once the two of them are alone, however, she doesn’t hold back and teases him with kinky insinuations, makes a pass at him, and finally claims him all to herself.