Shimai Ijiri
English title: Slave Sisters
Japanese title: 姉妹いじり
Type: OVA
Source: Visual novel
Episodes: 2
Status: Finished Airing
Aired: Dec 17, 1999 to Mar 17, 2000
Duration: 30 min per ep
Rating: Rx - Hentai
Studios: Y.O.U.C, Phoenix Entertainment
Producers: Digital Works
Licensors: Critical Mass Video
Genres: Hentai

Two sisters are orphaned, their parents left them only debts, in order to pay them and get themselves a comfortable life, they have to become slaves for a dark organization, and they begin their training under the guide of a man who uses words and reasoning as his only tools, and he is determined to make them the perfect slaves, if he succeds, he will be able to retire from that organization. 

(Source: ANN)