Mikogami Aventure

Toru Hazuki is a student of divinity. His family manages a shrine, where he will someday become the priest. One day, he is invited to 'Moegi Shrine' as a substitute priest and falls in love with the Moegi priest's second daughter, Aoi. She used to be shy, but once she experiences pleasure, she becomes very sexually active. Toru is ecstatic about it, but he doesn't know what he's go to be put through

Aoi's sisters, Midori and Akane, and their stepmother, Ayano, keep asking Toru questions about his sex life. Further more, Aoi's best friend, Ai, who happens to be a lesbian, tries to steal her from him. Will Toru be able to stand these energetic girls and be happy with Aoi!?

[From Gamelex]