On Christmas Eve, Hiro Hirono encounters Miyako Miyamura, a carefree girl who takes his bicycle to chase a purse thief. After Hiro finds his bike broken and Miyako passed out, they unexpectedly spend Christmas Eve together. When they learn they attend the same high school, their accidental connection grows deeper. This stirs jealousy in Hiro's childhood friend Kei Shindou, whose innocent outlook attracts Kyosuke Tsutsumi, a womanizing photographer seeking the perfect image.
Meanwhile, Renji Asou, a boy who dreams of being a girl's knight in shining armor, meets Kei's twin sister—the extremely shy Chihiro Shindou, who spends her time reading alone—at an abandoned train station. They quickly become friends and decide to write a novel together. But when Renji uncovers Chihiro's secret, his childish ideals face a serious challenge.
Guided by two enigmatic adults, these young people's relationships become intertwined in a poignant story of love, rejection, acceptance, and memories.