Grumble Grumble Grumble
It's a OVA that pretends to be hentai, but instead is just another ecchi romance series. The series is about a horny guy (who's a teacher) who hits on girls he just meets, (who turns out to be the daughter of the local Yakuza boss). Girls father decides that daughter needs a high school education, and sends her off to live with the guy, (with the implied threat that if the girls honor is violated...)
Not an outstanding series as ecchi OVA series go. If you want something along the lines of ecchi relationship series, then go with 'Sakura Diaries' which is now in a new re-release from ADV Films. Also, 'Golden Boy', a series about a guy who likes to love them and leave them, is another outstanding ecchi romance.