High school student Yuta Asamura begins living with his stepsister Saki Ayase and her mother due to his father's remarriage. Both Yuta and Saki, who hold cautious values regarding relationships between men and women, agree to live with an appropriate sense of distance between them.

A month has passed since Yuta and Saki started living together. As Yuta starts to understand the ambiguity of their relationship, Saki asks him for help studying modern literature. The two work together to prepare Saki for a test retake.

When Yuta is killing time in the library, Maaya confronts him and asks if he has feelings for Saki. After the parent-teacher meetings, Saki attends the open campus event at a prestigious women's college and is confronted by a particularly nosy professor.