Koharu Yūki is a character from the 1980 anime television series Tondemo Senshi Muteking. She is the mother of the protagonist Rin Yūki and his older brother Sonny Yūki, and the wife of the eccentric scientist Dr. Dankichi Yūki. Her professional role is that of a police chief, a position she holds with competence and authority. Her notable abilities and reputation lead to her being assigned a transfer to Japan, which precipitates the family's relocation, excluding Sonny, to a Japanese neighborhood for the latter part of the series.

Koharu's personality is defined by a blend of maternal warmth and professional assertiveness. She cares deeply for her family and often manages the household with a firm but loving hand, especially when dealing with her energetic son Rin and the bizarre situations caused by the alien threats. As a police chief, she is duty-minded and capable, yet she remains unaware of her son's secret identity as the superhero Muteking and the true nature of the alien activities she occasionally investigates.

Her primary relationships are with her immediate family. She shares a dynamic with her husband, whose outlandish claims about aliens she tolerates with a mix of concern and exasperation. Her role in the story is largely that of a nurturing yet authoritative parental figure, providing a sense of normalcy and grounding for the domestic comedy. She also serves as a link to the broader law‑enforcement response to the Kurodako Brothers' schemes, though she never discovers her son’s involvement in the superheroics. Her transfer to Japan and the family’s adjustment there mark a significant development in the series' setting, but her core role as a supportive mother remains consistent throughout.