An intelligent and beautiful girl who becomes a serial killer who leaves handmade music boxes after each murder. Yukine's motives are largely unknown, but she is apparently targeting Kiyotaka and the Blade Children for revenge. She is the sole holder of the Mikanagi File, with its information contained entirely in her memory - no concrete records of the file exist. Her father, Fusai Amanae, was a surgeon and her mother was a psychiatrist. Her father, as an associate of Professor Isabel Mikanagi, was entrusted with information concerning thirteen Blade Children erased from the list of eighty Blade Children held by Kiyotaka, the Watchers, the Savers, and the Hunters. After Mikanagi's death, the Amanae family fled to Japan with one of the Blade Children, a girl named Charlotte. When Charlotte's blood awoke murderously, Yukine's parents and Charlotte were killed in a resulting house fire, leaving Yukine the only survivor. When Yukine turned seventeen, she inherited her parents' bequest (Source: The Mikanagi File)