Satsuki and three of her friends are taught and compelled into performing a black magic ritual that can grant their wishes, by their classmate Shinobu Matsuda. However, the spells are actually a trap for the girls to have their souls stolen by the darkness, and Shinobu in reality is the avatar of an evil deity called Yamime (闇目). In the end, Satsuki learns that Shinobu was once her mother's classmate who mysteriously disappeared. Possibly upon her death, she was forever engulfed by Yamime. Satsuki seals her by first binding her using her red string and flashing her camera's light directly at her.