Tres Marias: Sannin no Sei Shojo
English name: Holy Virgins
Genres: Hentai
Type: OVA, Episodes: 2
Aired: Mar 16, 2001 to Jun 13, 2001
Studio: Y.O.U.C
Source: Visual novel
Rating: Rx - Hentai
Synopsis:
The locals know all about Dr. Fuwa. His reputation for taking advantage of his female patients has left him little to do except his nurse Megumi. When he`s suddenly called in to investigate a mysterious illness that`s been affecting the nuns on a remote island, Dr. Fuwa`s certainly not above having a little fun with the patients – each and every one of them a cute little nun-in-training. But will he be able to uncover the truth behind their terrible condition? 

(Source: AniDB)