Sana is a ronin (a student studying for university entrance exams) aiming for the University of Tokyo. Her life consists only of going back and forth between cram school and home, and she's accumulating a lot of frustration and sperm. Like looking for something to masturbate to, she quickly finds a sex partner using an app. Sana isn't looking for pocket money, but purely for sex. It's so easy to find a sex partner with just one finger. I want to get it off soon.