A middle-aged bachelor adopts a little girl when she is rejected by the rest of his family.

Reconnecting with her biological mother and her new family has put Rin at peace with her unfortunate beginnings. Now, becoming a big sister is cause for happiness for the levelheaded young woman. But despite this closure, all is not roses. The world around her seems obsessed with romance-Kouki still vies for Rin's affection, Reina jumps between relationships, a classmate shows his interest in Rin herself. Yet for Rin, love isn't turning out quite the way it's supposed to. Trapped between her head and her heart, will Rin be able to sort out her feelings before someone else picks up on them to disastrous effect?