In the bustling heart of Shinjuku, the former mercenary known as Umibozu, whose real name is Hayato Ijuin, tries to live a quiet life running the Cat's Eye cafe with his wife Miki. However, peace is a luxury he can rarely afford. Despite his intimidating height, bald head, and permanent sunglasses—necessitated by the gradual loss of his eyesight—Hayato possesses a surprisingly gentle heart, and he often finds himself using his unique skills to resolve the troubles of his customers and neighbors.

The narrative is largely episodic, with each chapter presenting a new, self-contained incident. As the master of the cafe, Hayato becomes an unlikely fixer for the community around him, tackling problems that range from the mundane to the dangerous. He helps a little girl find a lost cat, assists a woman in getting revenge on a scam artist, and aids a police officer in reconnecting with her estranged grandmother. His past as a deadly operative and his friendship with the legendary City Hunter Ryo Saeba often give him the edge needed to handle situations that spiral out of control, but many of his challenges are resolved through empathy, patience, and his surprisingly gentle touch with a coffee grinder.

The story explores the stark contrast between Hayato's fearsome appearance and his unassuming, almost shy personality. His deep care for Miki and the found family he has built at the cafe serves as his primary motivation, grounding the series in themes of warmth and human connection. While set in a modern-day Shinjuku, the tone is markedly more relaxed and heartwarming than the original City Hunter, though it retains a nostalgic connection to the franchise's action roots through mentions of Ryo and other familiar characters. The series ran for five volumes, comprising thirty chapters published between 2018 and 2021.