Detective Chono is a supporting character who appears in the later story arcs of 20th Century Boys, primarily introduced when the narrative jumps forward to the year 2014. He is a young and relatively inexperienced police detective who operates in a Japan that has transformed into a near-totalitarian state under the influence of the mysterious cult leader known as Friend. Chono is characterized by a notable lack of confidence that contrasts sharply with his genuine ambition and sound detective instincts. He is depicted as naive and easily intimidated by his longer-serving superiors as well as the power structures within the local community, which often casts him in the role of a character providing moments of awkwardness or light relief, even as the world around him grows increasingly dark and oppressive.

Despite his personal insecurities, Chono possesses a deep-seated dedication to justice and a persistent nature that drives him to uncover the truth. His initial role in the story serves as a compelling lens through which the reader witnesses the full extent of Friend’s influence over societal institutions, including the police force and the church. His investigations and his position as an officer allow for a grounded perspective on how the regime exerts control and eliminates dissent, making his character an important vehicle for world-building in the second major timeline of the series. Although he begins as a figure of comic relief due to his subservient and bumbling demeanor, his role evolves to become more significant as he follows the clues he uncovers to chilling conclusions.

A key relationship in Chono's arc is formed with Kanna, the niece of the original protagonist Kenji. Chono eventually uses his position to help Kanna, aligning himself with the resistance against the Friend regime, which demonstrates his moral core overriding his earlier timidity. This alliance marks a turning point for his character as he moves from being a passive observer within the corrupt system to an active participant in opposing it.

Chono’s development is further highlighted by changes in his circumstances later in the timeline. In the year 2018, he is no longer a detective but has been relegated to the role of a guard at a brutally run border town. In this harsh environment, he remains fundamentally unchanged in his values; he is still depicted as an honest officer trying to do his job with integrity, even though he now serves within a corrupt military junta rather than a corrupt police force. This consistency in his nature, set against the backdrop of his drastically reduced circumstances, underscores his resilience and unwavering commitment to honesty, even when that quality offers him no personal advantage or safety. His persistence eventually leads him into significant situations, such as being called to investigate reports of an "alien invader," which ties his path back into the central narrative surrounding the return of Kenji and the final confrontation with Friend.