Koji Nagasaki is a supporting character in the anime DEVILMAN crybaby, serving as the manager and photographer for Miki Makimura. He comes from a difficult background, which drives his ambition to become a respected reporter and escape his current line of work. His personality is marked by a blend of charisma and persistent, sometimes annoying, determination. While he is not inherently malicious, he is aware that his work is questionable and feels a strong desire to improve his standing. In the story, Nagasaki's role is that of a minor antagonist of sorts: he persistently follows Miki and is later possessed by the demon Gelmer, becoming a vessel for the demon's power. This possession turns him into a threat that the protagonist Akira Fudo must confront. His key relationships include his professional connection to Miki, whom he photographs and manages, and his indirect link to Akira and Ryo Asuka, who become involved when he is transformed. Physically, Nagasaki is depicted as tall and thin, with a prominent jawline, sunken cheeks, and a shaved hairstyle. His notable abilities are not innate; rather, his significance lies in being a human host for a demon, which grants him supernatural strength and aggression during the possession. His character arc illustrates the theme of human vulnerability and the corruption that can arise from desperation, as his initial dreams of becoming a journalist are overtaken by his role as a pawn in the demonic conflict. He does not experience redemption or substantial personal growth, serving primarily as an obstacle and a representation of the dangers lurking within everyday society.