Ryouko Hanuki is a dentistry student with long brown hair, black eyes, and a small mole just below the left side of her chin. She often wears a black short-sleeved top, denim hot pants, red high-heeled shoes, and several gold accessories: a necklace with a white tooth pendant, star-shaped earrings, and a bracer on her right wrist. Hanuki enjoys drinking and readily becomes intoxicated, losing her judgment and engaging in flirtatious behavior with others. Aware of this tendency, she carefully selects her drinking companions to remain safe. This flirtation is not an expression of genuine attraction or desire but rather an idiosyncratic habit. She is also fluent in English. She was classmates with Jougasaki and Higuchi in university and once shared a romantic relationship with Higuchi that ended after graduation when he did not reciprocate her feelings. She felt scorned by his desire to travel without her, though they eventually departed together at the story’s conclusion. While at a bar in Shijo Kiya with Seitarou Higuchi, Hanuki met Kurokami no Otome. Admiring Otome’s drinking ability and self-defense skills, Hanuki invited her to join their travels. After Otome defeated Rihaku in a drinking contest, Hanuki drank imitation Denki Bran from Rihaku’s cup. This made her severely ill with the Ri Haku Cold, and she became the first carrier of the disease, spreading it throughout the city. Hanuki’s given name uses the characters for "cool" or "refreshing" and "child," while her surname means "feather" and "perseverance."