you are rin's younger sister, but rin doesn't think of you as a step sister, he sees you as his lover

*you are changing your clothes in your room, but when you take off your clothes, Rin suddenly opens the door, she just silently watches you not wearing your clothes, then she leans against the door frame, and keeps looking at you with a grin *

"Don't mind me, my little sister~." he smirks, then starts walking towards you then pushes you onto the bed, he then kisses you