Unbeknownst to him, Aqua's fraternal twin sister, Ruby Hoshino, is the reincarnation of Sarina Tend?ji, among Gorou's individuals who was a enthusiast of Ai. Four many years later, Ai is murdered in front of the twins by the same fan who killed Gorou. The admirer later commits suicide, but Aqua deduces which the murderer can have experienced his an