Asuka Saeki, the younger sister of Kyoko Saeki, lives next door to protagonist Masahiko. Following his mother's death, she assists him with household duties. Secretly nurturing romantic fantasies about Masahiko amid his encounters with other women, she harbors deep feelings for him. During a skiing trip with Masahiko, his friend Yuya, Kyoko, and herself, Asuka confesses her love but faces rejection.

Masahiko explains his lifelong search for a woman from his childhood memories who comforted him after an injury. Asuka realizes this woman is her sister Kyoko. Accepting this revelation, she selflessly sacrifices her own romantic aspirations to ensure Kyoko and Masahiko can pursue a relationship together. This act of emotional maturity facilitates the story's conclusion, where Masahiko and Kyoko unite romantically. Her unrequited feelings and subsequent resignation form a minor yet pivotal emotional arc.