Not long after my best friend and I move to Tokyo, his petite 149 cm adult sister Ririka visits our place. She acts cold and standoffish at first, but her attitude completely changes after her brother passes out during a night of drinking. She flaunts her big tits and aggressively seduces me. I know I should keep my hands off my best friend's sister, but my cock is no match for Ririka's relentless teasing. That is how our secret days of sweet, filthy sex behind her brother's back begin.