This is a game where you do n*ght crawling without waking a "tsundere" sister-in-law. As you interfere with your sister-in-law, you can undress, lick (cunt, arse), rub, titty fuck or fingerbang her.
The female character had boy friend.You survival with her, let her feel good with you and clear her boyfriend without her knowledge. Then got her! sex with her! let her addicted to sex!