On Christmas Eve, a girl chases a thief who stole her purse and ends up stealing Hiro Hirono's bike in the process. Hiro goes after the thief but instead finds the unconscious girl, Miyako Miyamura, and a destroyed bike. Once Miyako wakes up, Hiro makes sure she is safe and they end up spending the evening together. Miyako attends the same school as Hiro and they become closer, causing Kei Shindou, Hiro's childhood friend who secretly likes him, to become jealous and a love triangle ensues. In addition to this, the show follows the story of Renji Asou who meets Chihiro Shindou, Kei Shindou's twin sister, at an abandoned train station. Despite her shyness, they connect well and agree to meet there every day. However, Renji discovers that Chihiro was in a car accident years ago, limiting her memory to only 13 hours. Despite this, her dream is to write a book, and Renji is determined to help her achieve it while navigating the obstacles of her illness.