Akihito Narihisago

He was once a happy man with a family. Two years ago, his daughter was assaulted and later bashed to death by the serial killer, the Challenger. This later spiraled Ayako's severe depression, and despite Narihisago's best efforts, committed suicide out of grief soon afterwards. Disdained and vengefully driven, Narihsiago shot the Challenger out of vengeance after finding out his true identity, unintentionally saving Kiki Asukai. After this decisive victory, Narihisago was sentenced to prison for Katsuyama's murder. Two years later however, having killed someone, he now is capable of entering ID-Wells and retrieving information about serial killers using their murderous intent. Once he enters the wells, he is known as Sakaido "the brilliant detective", with no prior memory of his real identity, he assists in investigating and analyzing the serial killer's subconsciousness. Over the next year, he would go on to aid in the capture of at least four serial killers, among them being "the Face-lifter", "Tongue-tearer", "Arm-twister" and "Thigh-severer".