Kogoro, also known as 556, is a space detective in the anime and manga series Sgt. Frog. He is a human-like alien who grew up with Keroro as a childhood friend. Despite his self-proclaimed profession as a detective of justice, he is remarkably poor at his job. His investigative methods are ineffective, he struggles to solve even simple cases, and he frequently becomes sidetracked by childish interests. He lives in a rundown apartment and operates on a very limited budget. Externally, Kogoro projects unwavering positivity, wearing a perpetual grin and laughing frequently, even when he is depressed or unemployed. This cheerful facade hides his true emotions, which only his younger sister Lavie is able to perceive. He has a peculiar fascination with collecting colored boxes, which he hoards without any practical purpose. His role in the series is primarily as a comic relief character, appearing in episodes that parody space detective tropes. His dedication to his own sense of justice is genuine, but his incompetence and eccentricities consistently undermine his efforts. His relationship with Keroro is defined by their shared history, and his interactions often highlight how his ambitions clash with his actual abilities. Over the course of the story, Kogoro remains largely static, maintaining his upbeat outlook and flawed detective skills without significant personal growth. His notable abilities are limited to his physical resilience and his capacity to maintain his cheerful demeanor through hardship, as well as his quick reflexes, which are sometimes shown in action scenes.