The protagonist was spending his days in frustration, forced to watch his best friend flirt with his cool, busty and beautiful girlfriend, Rinna, at their part-time job.

Then one day, Rinna confides in him that her relationship isn't progressing because her boyfriend is too shy. After talking to her a bit, it becomes clear that she herself is also quite shy and completely ignorant when it comes to sexual matters.

This is the perfect opportunity!

The protagonist convinces her that sexual contact is essential to deepen a relationship and declares that he will take on the role of 'sex instructor' for her. Rinna, completely ignorant about sex, naively accepts, and the protagonist succeeds in stealing her virginity, which should have been given to her boyfriend, and having creampie sex with her! Thus began his days of taking advantage of her sexual ignorance, indulging in wanton, erotic NTR (Netorri) and training!