Nishikiori operates as a seasoned officer within Japan's Cabinet Intelligence and Research Office, specializing in supernatural phenomena investigations. He begins with deep skepticism toward magic and spirits but shifts into a dual role as liaison and bodyguard for the Ougi sisters, Shoko and Maiko. His duties involve bridging their exorcism work with official government protocols and supplying practical investigative support for occult crimes like curses and possessions.

During the team's initial mission in Nara—centered on the Ikeda family curse—Nishikiori transitions from doubt to acceptance of supernatural forces. This evolution establishes him as a reliable ally, leveraging conventional police tactics and resources to augment the sisters' spiritual abilities. His grounded, non-magical methods create a dynamic contrast yet functional synergy with mystical colleagues like the spiritualist Kenmochi.

His character remains defined by professional function across all adaptations, including the 1989 film and later media, emphasizing pragmatic contributions against supernatural threats.