Twin sisters Mio and Mayu Amakura are visiting a childhood play spot, when Mayu follows a mysterious crimson butterfly deep into the forest. Concerned for her twin, Mio follows Mayu and the two girls are led to a lost village. When they reach the village they enter an old house, where they find the Camera Obscura. Mio must uncover the mystery behind the Crimson Sacrifice Ritual while chasing her sister, who is becoming increasingly possessed by the evil spirit of Sae, the last girl to be sacrifice
