Sora no Iro, Mizu no Iro
English name: Color of Sky, Color of Water
Genres: Hentai
Type: OVA, Episodes: 2
Aired: Jul 28, 2006 to Jun 27, 2008
Studio: Himajin Planning
Source: Visual novel
Rating: Rx - Hentai
Synopsis:
Asa &amp; Natsume are both in love with Hajime Saisho. Instead of fighting over him, they both promised to share him equally. However, both girls have to leave him by the end of the summer. As the summer days go by, they each spend their precious time with Hajime, while the day of their fated departure draws near. 

(Source: ANN)