Oppai Heart: Kanojo wa Kedamono Hatsujouki!?
Japanese title: おっぱいハート～彼女はケダモノ発情期ッ!?～
Type: OVA
Episodes: 2
Source: Visual novel
Genres: Hentai
Studios: Nihikime no Dozeu
Duration: 28 min per ep
Rating: Rx - Hentai

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)