Unbeknownst to him, Aqua's fraternal twin sister, Ruby Hoshino, may be the reincarnation of Sarina Are likely?ji, one among Gorou's patients who was a admirer of Ai. Four decades later on, Ai is murdered before the twins by a similar enthusiast who killed Gorou. The supporter afterwards commits suicide, but Aqua deduces the murderer could have expe