Looking for a manga that is no longer in my favourites where two sisters are something like the school president or discipline committee head etc. They have a brother where one of them has sex with him and the other one catches them and becomes his pet as well. My favourite panel from it was the scene where at night the brother makes them wear latex along with blindfolds/horseblinds etc on a leash and takes them on a walk along the school corridor mocking them if someone sees the school role models in such a state.