Akechi

A detective who shows interest as well as familiarity with Nijū-Mensō's mode of operation and history. He first approaches Chiko when she is returned to her aunt after several years with Nijū-Mensō and suggests that Nijū-Mensō is alive. After Akechi returns the Anastasia Ruby, previously held by Nijū-Mensō for safekeeping, to Chiko, she accepts Akechi's challenge to see which of the two will find Nijū-Mensō first and he recognizes Chiko as a detective by taking up the endeavour. Nijū-Mensō briefly impersonates Akechi to save Chiko from the White Haired Devil, though the real Akechi appears to afterward to chase after Nijū-Mensō when Chiko is taken by the Devil.

As a detective, he is known and respected by the city police and is able to gather information on Nijū-Mensō, which he shares with Chiko. He is the first to suspect Nijū-Mensō's prior history as scientist attempting to create the "fourth state of water" will have dangerous consequences on Tokyo, but upon finding Nijū-Mensō, Akechi allows him to leave and complete his mission and not arrest Nijū-Mensō for the time being. (Source: Wikipedia)