Both in appearance and personalities, twin sisters Ageha and Hana Mizuki could not be any more different from each other. Separated at birth until second grade, Ageha had grown up in the countryside, being raised by her grandmother, while Hana lived in the city with their parents. Due to their contrasting upbringings, the quiet and reserved Ageha constantly lives in the shadow of her outgoing and charismatic sister.

During her childhood, Ageha befriended a boy named Ryuusei Koike and has been in love with him since. When she moved back in with her parents, the two lost contact with each other, but she was surprised to see him again in high school. Even so, she cannot bring herself to talk to him, much less confess her love for him. Seeing her woes, a mysterious man tells Ageha if she proclaims her love out loud, then Ryuusei will surely return her feelings.

Thinking he is delusional, Ageha humors the idea, only for Ryuusei to enter the room and remember their childhood together. Their reunion is short-lived, however, when Hana decides to swoop in and steal Ryuusei from Ageha out of jealousy. Just when she loses hope of ever being with him, the stranger from before reappears, promising to help Ageha take Ryuusei back.