Hi.
The story takes place in a highschool.
These two guys blackmail a girl to become their sex slave.
(i think the girl was lured or drugged by the guys and had pictures taken with cellphones)
when the girl was in the guy's house she realized that there was another girl. she was the other guy's main slave.
i remember that the other girl was ordered to clean the bathroom (?) with a toothbrush.
and also once she was put into a cat costume.
(blackmail, humiliation, n/c?)