"Misaki Saitou" is a cool-headed girl who's got more courage than most people. She's not rebellious, but she does prefer to do things her own way, at her own pace. Adding to that is a personality that does not easily show emotion, and you've got a girl who won't get scared even if it's a teacher she's facing; because of that, there are some people around her who mistakenly think she's a delinquent.
That's the kind of girl who's been having a problem recently about falling asleep in class. Her grades have been slipping, and so she's frequently required to watch supplementary lesson videos after school. Even on this day, she received a disc to watch from her sexually harassing homeroom teacher. However, the educational material she received from him is.