Shiroi Tsuki Joshin(2003)

Shiroi Tsuki Joshin

This manga is the prelude of Ai To Yokubou Rasen. Since they were young, twin brothers Ryuuga and Taiga received different treatment from their mother. Ryuuga was doted on by his mother while Taiga received the opposite. Eventually Ryuuga's Mum started to show her strong love desire to have Ryuuga by her side, eventually both of them engaged in a forbidden sexual relationship. This story is full of forbidden smut stuff, but ought to read this manga as Ai To Yokubou Rasen storyline gets more interesting and tragic...
(Source: TCManga)