Fortune Arterial: Akai Yakusoku

Synopsis

The episode starts with Haruna, Kanade, and Heiji wanting to have a tea party in Kohei's room also inviting Erika and Shiro. The next day they all go out shopping together. The next day, back in school, Iori reveals, while playing a "serious" board game, that he is indeed a vampire just as Kohei suspected with Erika confessing the same thing. Iori claims he has no intention to suck Kohei's blood and offers Kohei a chance to join Student Council but if Kohei refuses to join Iori will be forced to erase Kohei's memory. Finding some difficulty in refusing, Kohei nonetheless refuses and is willing to start over at the academy. Iori leaves and asks Erika do the "job". Erika, revealing her fangs and vampire power to Kohei, finds herself unable to erase Kohei's memories, with the latter wanting to keep his memories. Later, Kohei agrees to join Student Council.

(Source: Wikipedia)