Yukimi Yasuda is a student at Seishuu High School and a star athlete on the track team, having transferred at the start of the school year. She has known Katsuya since middle school, where she developed a romantic interest in him. After transferring, she actively pursues Katsuya, creating tension with Yuri, who also harbors feelings for him.

Characterized by loud, outspoken confidence and demanding nature, Yukimi deliberately uses her feminine charms, offering dates and promises of kisses as rewards. Her primary motivation is winning Katsuya's affection and becoming his wife, leading her to support him through cooking and cheerleading. She stands in contrast to the gentle, timid, and conforming Yuri.

Yukimi persists despite Katsuya's indecisiveness about his feelings. His reluctance to reject her outright or confess his preference for Yuri fuels her ongoing hope and frustration. Her pursuit grows more complicated when Jirou, the younger brother of Yuri's admirer Kentarou, joins the Seishuu baseball team and develops genuine feelings for her. This introduces a new dynamic as Jirou actively pursues Yukimi while she remains focused on Katsuya.

Yukimi eventually confronts Katsuya about his ambiguous behavior, prompting him to clarify his feelings for her and resolving the uncertainty in their relationship. Her family background includes interactions with her grandmother, and her birthdate is known, details providing personal context absent for others like Yuri.

Beyond being a romantic rival, Yukimi receives significant narrative focus in the second installment, where her perspective and emotional journey drive key plot developments.