On Christmas Eve, Hiro Hirono's bike gets taken by a girl pursuing a thief who stole her purse. When he catches up, he discovers the girl, Miyako Miyamura, unconscious and his bike damaged. As they converse and spend the evening together, a bond forms between them. Learning that they attend the same school, their companionship deepens, stirring Miyako's feelings for Hiro. The arrival of Kei Shindou, Hiro's lifelong friend harboring unrequited love, sparks jealousy and a complex love triangle. Parallel to this, the narrative delves into Renji Asou's tale. His encounter with Chihiro Shindou, Kei's twin with a memory limit of 13 hours due to a past accident, unfolds at an old train station. Despite Chihiro's challenges, their daily meetings blossom a friendship. Renji, discovering Chihiro's aspiration to write a novel, embarks on aiding her in achieving this dream while assisting her in navigating the obstacles posed by her condition.