18+ Gibo

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)