Dusk Maiden of Amnesia Season 1 Episode 7

Maiden of Oblivion

Teiichi notices Yuuko has been acting strange as she unknowingly keeps lashing out everytime he spends time with Momoe. He confines this to Kirie who tells him she saw the shadow ghost again. With the strange things she's been noticing lately, Kirie concludes the shadow ghost is actually a literal split personality of Yuuko which contains the darker side of her. Soon Kirie, Teiichi and Yuuko encounters "Shadow Yuuko", who reveals to them she is the embodiment of Yuuko's hatred and the painful memories she wanted to forget. Yuuko runs away denying what the Shadow said where Teiichi catches up with her at the Rock of Curses when he notices it is actually a memorial stone dedicated to the towns folk who died in a plague 60 years ago which also includes Yuuko's name. Realizing all of the school's ghost stories are actually connected to Yuuko, Teiichi now knows how Yuuko died; she was offered as a living sacrifice to stop the plague 60 years ago.