Kanata Haruka lost both parents and has no remaining family. On top of that, a terminal cancer diagnosis has given him a limited amount of time — not enough to see another spring. His two childhood friends, Kousuke and Kanae, are the remaining anchors of his life. Kousuke knows about the illness and has been quietly helping with tasks that are growing harder for Kanata to manage. Kanata cannot bring himself to tell Kanae — partly because he can see that she has feelings for him, and partly because he cannot bear what the conversation would do to her. As the seasons move from late autumn toward winter, a blonde girl named Christel arrives and introduces herself: an immortal vampire, uninvited into a life that is already running out of time.