Anime XXX - Oku-Sama Wa Moto Yariman - 1

Based on a doujin game by Orcsoft. Yuuto lives alone with an apartment complex, although he is not lonely as a result of his neighbours Megumi, Anna, and Mako. While he enjoys their company (and their appearance), he is a little upset that people constantly treat him like a child, not a man. Things alter on the night of his birthday, when, following the party the three arrange for him, Megumi informs him that she will do something for him as a birthday present. It's the start of Yuuto's steamy summer vacation with the three seductive ladies...