Sōma invites Himeko to the amusement park on a date and Chikane tries her best to help Himeko prepare for her outing. While on their date, Tsubasa, the First Neck of the Orochi, attacks the couple as Sōma tries his best to protect Himeko.
The highborn Himemiya Chikane is cool and aloof, the perfect young lady of good breeding. Kurusegawa Himeko is devoted to her, and secretly her friend. Their lives are undisturbed in their school, until an ancient evil suddenly rears its head. To combat it, Chikane and Himeko must take on the roles of shrine maidens of the Moon and Sun.