Kiri Ichidō is the younger sister of Rei Ichidō and the daughter of Takuseki Ichidō. She possesses a sharp mind and displays a level of maturity that goes beyond her years, embodying the archetype of the responsible sibling in contrast to her older brother's tendencies as a clumsy and troublesome family member. Her father openly favors her, which solidifies a family dynamic marked by parental preference.

In terms of personality, Kiri is academically gifted and socially adept, excelling as a respected student who is admired by her peers for her composure and achievements. However, this admiration diminishes once her connection to Rei becomes known, as his escapades draw ridicule and embarrassment, forcing her into the role of the elder brother who is a disappointment. Her calm and collected demeanor helps to stabilize the Ichido household, balancing out the eccentricities of both Rei and her father, yet this also leaves her emotionally adrift within their chaos.

Kiri's primary motivation and role within the story revolve around managing the consequences of her brother's actions. Despite her frustration with Rei's behavior, she navigates a tense dynamic with him that fluctuates between exasperation and an unspoken, deep-seated loyalty. Her notable abilities include her academic excellence and strong social competence, which contribute to her standing as a highly regarded student. Her development is centered on her struggle to maintain her own identity and reputation while being constantly overshadowed and embarrassed by her family, particularly Rei, whose antics define much of her personal conflict.