Kojire ni Kojireta Gikyoudai no Hanashi

Rikka is a working woman with a college student stepbrother named Rin. Over the past decade, Rin has quietly developed affection for his attractive and dependable stepsister. He believed she viewed him only as a sibling and that expressing his feelings was impossible—until the two find themselves on what appears to be a "practice date." For the first time, he addresses her by her first name and holds her hand. As they continue to behave like a couple, Rin’s repressed emotions begin to surface.