Prism Magical: Prism Generations!
Genres: Comedy, Ecchi
Type: OVA, Episodes: 1
Aired: Aug 27, 2010
Studio: Asahi Production
Source: Visual novel
Rating: R+ - Mild Nudity
Synopsis:
* An exclusive OVA produced for PAJAMAS SOFT 10th Anniversary-Project Prism Magical: Prism Generations! and included with the professional package of the game.

There is a small town on the sea. Raika just enjoys his school life with Ibuki, his old friend, and Yuri, his maid. However, his father is actually a magical girl (?). Also, a group of magical girls come to his school to look for a treasure stone called Mana Prism. Though he doesn't want to wear a girl's costume, he is forced to be a magical girl as well! "Come back, my peaceful life!" To save his school, his battle against the magical girls starts now! 

(Source: AniDB)