Yuu Sanpei, a child who has just turned into a teenager. His mother died when he was a baby and his father often traveled abroad because of his busy work. Yuu was finally entrusted to his neighbor, Natsuki Kamiya. And an extraordinary thing happened when he passed the high school entrance selection. For the first time in his life he experienced his first sexual experience with a MILF who had been taking care of him all this time.