"No, manager, the first time I told him... Oh, it's going crazy. I wonder if it would be easier if you could let me in..." Yumino-chan, a rookie part-time worker with a boyfriend who works at a convenience store, is one day found out the password of her smartphone by the store manager, who has a hobby of voyeurism. "Practice!" is a message sent out of now by my boyfriend, who has only kissed me yet. Yumino-chan, who has no experience, is confused, but it was a 'fake message' from the store manager who pretended to be her boyfriend in a long-distance relationship. The store manager forcibly offers to be in charge of education for Yumino-chan. Yumino-chan, who doesn't know anything, decides to receive erotic guidance from the store manager out of her single-minded feelings for her boyfriend. From that day on, an affair in the manager's office takes place in the name of guidance. Yumino-chan stubbornly refuses to have sex, but one day in the pleasure of being indoctrinated, her reason finally collapses.