Gibo
English title: Stepmother's Sin
Japanese title: 義母
Type: OVA
Source: Visual novel
Episodes: 2
Status: Finished Airing
Aired: Oct 5, 2001 to Jan 11, 2002
Duration: 29 min per ep
Rating: Rx - Hentai
Studios: Y.O.U.C
Producers: Digital Works
Licensors: Central Park Media, Critical Mass Video
Genres: Drama, Hentai

Yusuke's been very naughty. He's seduced his father's fiancee; transforming her into a debased slave to his own twisted desires. But as his hold on her tightens, his sanity slips, and the forbidden family fun descends into a nightmare of lust! Trapped in madness of their own creation, they will pay the ultimate price for a stepmother's sin!

(Source: RightStuf)