Momo Shirai is a young police officer who works under the supervision of Inspector Oniyama in the anime series Mysterious Joker. She has short blonde hair with spiky ends and is usually seen wearing a pink and white police uniform accompanied by a black, white, and pink hat. Her appearance gives an impression of youthfulness and energy, which contrasts with the more serious demeanor of some of her colleagues.

In terms of personality, Momo is described as peppy and energetic, often displaying a bright and approachable attitude. Compared to the other female officer, Ginko Kurosaki, Momo is the more easygoing of the two. Despite her cheerful and somewhat casual demeanor, she remains dedicated to her profession and shows a strong sense of duty. She works effectively as part of a team, cooperating with Oniyama and others in their efforts to capture the phantom thief Joker.

Momo’s primary motivation is to uphold the law and assist in apprehending Joker. She takes her responsibilities seriously, even though her lighthearted personality might initially suggest otherwise. Her role in the story is that of a supporting law enforcement officer who occasionally appears alongside Oniyama in pursuit of Joker. Her key relationship is with Oniyama, her superior, and she also shares a collegial dynamic with Ginko Kurosaki, though the two have contrasting temperaments.

Notable abilities include her capacity for teamwork and her competence as a police officer. She is able to coordinate with others during investigations and heist-prevention operations. Detailed information about her background prior to joining the police force, deeper personal motivations, or significant character development across the series is not extensively documented. She remains a consistent supporting presence throughout the anime, contributing to the comedic and action-oriented interactions between the police and Joker.