Shiori Saitō, granddaughter of Shouzou and Ine Saitō, is Mino Saitō's cousin in the extended Saitō family. She attends Kitamachi High School through a special academic pathway earned by her exceptional intelligence and scholarly achievements. Her personality displays a cold, serious demeanor; she expresses herself bluntly and unfiltered, occasionally bordering on tactlessness. Despite this reserve, Shiori exhibits genuine warmth and concern for her grandparents, actively engaging in family activities with affection. Within the family, she contrasts with her humble, approachable cousin Mino. Shiori's role highlights her intellectual disposition and occasional emotional distance, yet underscores an underlying loyalty to her relatives. As part of the younger generation affected by her grandparents' rejuvenation, she observes and participates in their renewed experiences while steadfastly maintaining her academically centered identity.