Unbeknownst to him, Aqua's fraternal twin sister, Ruby Hoshino, may be the reincarnation of Sarina Tend?ji, amongst Gorou's clients who was a supporter of Ai. 4 several years later on, Ai is murdered in front of the twins by the exact same supporter who killed Gorou. The supporter afterwards commits suicide, but Aqua deduces the murderer could have