Mizuki Inuhiko attends Ikai High School as a classmate of Ouri Kagami, alongside Hiroshige Ushijima, Sumitori, and Nozomi Kasuga. Observant by nature, she actively campaigns to become student council president. Her appearance features waist-length brown hair and black eyes. Her surname, Inuhiko, combines the characters for "dog" (犬) and "boy" or "prince" (彦), while her given name Mizuki derives from "felicitous omen" or "auspicious" (瑞) and "tree" (樹). She was born on April 28, making her a Taurus with blood type O.

Narrative commentary describes her "tidal wave personality" as a force that drives others to persevere through difficulties, preventing them from losing motivation or giving up. Mizuki consistently displays confidence and proactively engages with those around her, yet distances herself from individuals who dismiss or ignore her. Though recognized as a complete and compelling figure within the narrative, her role remains minor with limited appearances across the series. Concrete information regarding her broader background, character development, or specific plot involvement across various media formats is not provided.