Oppai Heart: Kanojo wa Kedamono Hatsujouki!?
Genres: Hentai
Type: OVA, Episodes: 2
Aired: Oct 28, 2011 to Feb 24, 2012
Studio: Nihikime no Dozeu
Source: Visual novel
Rating: Rx - Hentai
Synopsis:
Ryuya has an older sister, Miya.  He lives a peaceful school life with his friends.  But one day, he and his friends accidentally drink a medicine juice.  Once you drink it, you'll become sexually sensitive and get excited.  The breasts of the girls who drink it will get bigger and they will need to have sex to cool down.  Also, to make a vaccine, they will need to get pregnant.  Ryuya starts having sex with the girls to cool them down and make a vaccine.

(Source: ErogeShop)