Euphoria (2011)

In this anime series which is an adaptation of nsfw game of the same title, the protagonist takato kiesuke and 6 others are locked up in a white room. They then are asked to play a weird game by a mysterious voice. One of the girls named miyako refuses to do so, at that moment the lights go off andwhen the light resumes she is chained on a torture set and is given electric shocks. Everyone gets horrified but kiesuke starts getting aroused, this is his secret his desire to assault and humiliate girls. And the show has only started!