Yamime The Dark Deity a.k.a The Dark Eye is an evil entity that possessed the body of Shinobu Matsuba, Satsuki's 'new' classmate. She appears at Satsuki's school after a ritual is held by a student at night after everyone had gone home and attacks the girl. Yamime, posing as Shinobu Matsuba using her stolen body, is introduced as Satsuki's new classmate. She has knowledge of black magic and convinces a group of girls (including Satsuki) to perform another ritual, saying that if they do, they could have anything they desire. The ritual was actually a trap for Yamime to steal the souls of the girls, and erase them from existence. After Satsuki discoveres the plan, Yamime appears at her house while her father and brother are asleep to attack her. Satsuki consults the Ghost Diary and is told to "bind her with red string and bathe her in sunlight." Satsuki finds she has no red string and instead draws red lines drawn across the mirror in place of string so when Yamime looks into it it appears as if she were tied up. To 'bathe her in sunlight' she uses a camera flash. The next day, the girls who had been erased returned.
It is revealed that Shinobu was a classmate of Satsuki's mother who had gone missing under mysterious circumstances.