Hanae Yuiga is the widowed mother of Nariyuki, Hazuki, and Kazuki Yuiga. Her husband, Teruaki Yuiga, a world history teacher at Ichinose Academy, died from illness five years before the story's main events. As a single parent, she supports her family by working part-time at "Luxury Jewelry," a jewelry shop where Chiyoko Amada is her colleague. Financial constraints result in a modest lifestyle where eating sushi is a rare treat.

Sociable, cheerful, and kind-hearted, Hanae displays a keen interest in romance and visibly delights when observing couples. She warmly welcomes her son Nariyuki's friends, showing particular affection for Rizu Ogata and Fumino Furuhashi, whom she nicknames "Ri-chan" and "Fumi-chan" after finding them doll-like. While supportive of Nariyuki's efforts to secure a university VIP scholarship, she worries about the burden he places on himself to improve their circumstances. Following Teruaki's passing, she manages family affairs, entrusting his inheritance to Nariyuki.