After his mother's passing, Miwatari Yuu heads back to his birthplace, Ousuku, to live with his family. For countless generations, Yuu's family members have functioned as Shinto priests. Upon his arrival, Yuu meets a mysterious young woman who is in pursuit of the Northern Lights. Yuu experienced the Aurora as a child, despite others' skepticism, and was told by his mother that it was the Valkyries' armor etched across the sky. Yuu's destiny becomes intertwined with that of the unusual young lady and the aurora, pulling him into a battle between gods and humans!
