Kimura Mami cannot forget her first love. No matter who she dates, she ends breaking up with partners after a short time, probably since she seems to always be looking for traces of her first love. Even though her older sister has told her to change, she just can't help herself from chasing after his shadow. And that's because of that boy, Rin... Went missing 15 years ago. Then one day, she met Shiono Asuka, a man who looks exactly like Rin. After learning of Asuka's secret, Mami can't help but question if he actually is Rin... As she tries to recall the memories of her first love, she begins to learn the truth hidden behind Rin's disappearance.