Yorito is a high school student who enjoys photographing the sky. A chance encounter introduces him to Matsuri, but she is no ordinary girl—it turns out she is actually a 350-year-old Yaka, an immortal being that cannot go out into the light! As such, Matsuri has been forced to live a life of solitude, and Yorito is the first friend she's ever had. But there is much more to the Yaka than first meets the eye, and a sword-wielding man named Takeshi seems intent on harming Matsuri, but for what reason? Now thrust into a supernatural battle, will Yorito have the courage to protect their friendship for Matsuri's sake?