The protagonist lives a boring life of just coming and going to school. In his class there are three busty beauties, but because he is an introvert they are all faraway existences to him. Exciting things don't happen to his life, but even then he's able to have fun with his two otaku friends. But even a guy like him had a secret. Hiyori Mizukawa, one of the busty beauties in class, is actually his childhood friend and her place is also located in the same condominium building as his. Even more, they have this long-running connection where they study for tests together once a year. He thought it wouldn't be out of the ordinary for Hiyori to come over today, and she did. But her intention was to use her body to express her long-held accumulated feelings for him. And so this is where his road to becoming a playboy begins.