On Christmas Eve, Hiro Hirono's bike is stolen by a girl chasing a thief who stole her purse. He gives chase and finds her unconscious and his bike ruined. The girl, Miyako Miyamura, soon awakes and the two begin to talk. After making sure she is okay, they end up spending Christmas Eve together. Later, Hiro finds out Miyako attends the same school as him and they begin to spend more and more time together, Miyako developing affections for Hiro. Kei Shindou—Hiro's childhood friend who has long held a crush on him—begins to become jealous and a love triangle follows.