Unbeknownst to him, Aqua's fraternal twin sister, Ruby Hoshino, could be the reincarnation of Sarina Tend?ji, one of Gorou's clients who was a admirer of Ai. Four yrs later, Ai is murdered in front of the twins by exactly the same admirer who killed Gorou. The fan later commits suicide, but Aqua deduces the murderer could possibly have experienced