Shigure Komai is Chizuru Komai's older sister and a third-year student at Kagome Academy. Beautiful, intelligent, and serene, she possesses a composed demeanor and keen understanding of her surroundings. Despite her capabilities, she consistently avoids leadership roles or extracurricular activities, preferring to go straight home after school.

Shigure harbors deep romantic feelings for her younger sister but battles to suppress these taboo emotions. She maintains subtlety regarding her attraction, internally struggling with its intensity, a reserved approach contrasting sharply with Chizuru's more direct attempts to express affection.

Her character development centers on resolving this conflict. After Chizuru seeks advice from Momoko Naitou about confessing her love and initiates a kiss, Shigure experiences profound emotional turmoil. Seeking guidance from Shinobu Handa, she is encouraged to acknowledge the mutual intensity of their feelings. This helps Shigure accept that their emotions are too powerful to ignore, leading her to stop resisting the relationship.

The progression culminates in Shigure reciprocating Chizuru’s affections, solidifying their romantic involvement. This shift is highlighted when Chizuru kisses Shigure to alleviate her "heart pain." Shigure once referenced a school rumor about two girls in love in an art room, implicitly connecting it to her understanding of forbidden romance.