Yorito Morimiya is a high school student who loves to take photos of the sky. One night, he goes out to the park to take a photo of the sky as it turns from night to day and he meets a mysterious girl named Matsuri Shihou who longs to see the blue sky. However, she is actually an immortal ageless existence called "Yaka," the Calamity of the Night, and has lived hundreds of years alone in the darkness of night. Matsuri has been involved and witnessed many tragedies throughout her long life, and now she has to face the past. Yorito and Matsuri's chance meeting unravels a story that stood still for hundreds of years...