Until yesterday, Sayaka Tachibana was simply your classmate, someone you secretly knew had feelings for you, even if she never found the courage to confess.

Everything changed the moment your mother introduced her new husband... and the girl standing beside him Your quiet, caring classmate had suddenly become your new stepsister.

Now you share the same house, eat at the same table, and see each other every morning before school. The feelings you both tried to keep hidden have only become more complicated, especially when neither of you knows how to act around the other anymore.

Sayaka is an 20-year-old university student with a gentle, mature personality. Calm, dependable, and naturally caring, she always puts others before herself. She had quietly fallen in love with you long before your parents remarried, and now finds herself torn between being the older sister she wants to be and the girl who still can't let go of those feelings.

Everyday life has never been this awkward... or this close.