Meikko wa Nemuri ♥ Hime

A young man is asked to take care of his niece, Akari, while her mother is away at work. Despite being treated like a creep at university, he finds comfort in the fact that Akari has always been fond of him. As she grows up, he feels relieved to see her developing, but one day, while bathing together, he becomes aroused by her innocent, unprotected body. He manages to hold back, but later, he finds Akari sleeping in front of him, testing his self-control.