Synopsis
Mayu works as a psychological counsellor at a hospital. One day, she is counselling a young girl who is under her care. Mayu sits across from the young girl, who is unable to do anything other than say her own name, when unusual things gradually begin to occur around her.
Around that same time, Mayu's younger brother Kazuma goes missing. According to what his friend Yusuke said, Kazuma had mistakenly entered a forbidden site while making his name as a YouTuber, and had become rather strange after that. While looking for clues, Mayu watches a video that Kazuma had uploaded. She comes upon a video clip that is connected to the young girl under her care...
Relying upon clues to search for her younger brother, Mayu and Yusuke travel to Izu-Oshima island, where there is an obviously disgusting cave called 'Gyojakutsu'. A mysterious old woman tells the sad tale of the island's past, which involves Shizuko Yamamura (Mother of Sadako), Sadako, and the young girl. When Mayu learns the truth about Sadako, she is deeply moved...