Chika Itou, nicknamed Chi-chan, is a pragmatic and responsible 12-year-old sixth-grader who anchors her social circle as the steadfast "straight man." Her no-nonsense attitude and commitment to common sense starkly contrast her peers’ quirks, often grounding their antics with her disciplined focus on academics and routine. Miu Matsuoka, a close friend, playfully dubs her "uptight" and "cheapskate" for resisting impulsive fun or sharing homework answers.

As Nobue Itou’s younger sister, Chika steps into a caretaker role when their parents are away, meticulously managing household finances to curb Nobue’s indulgences in cigarettes and alcohol. Her maturity shines through her adept cooking, particularly her celebrated cookie-baking skills, which her group readily relies on—even as Nobue teasingly dismisses her "lack of distinguishing traits."

Chika’s bond with Miu balances exasperation with unspoken camaraderie. Though visibly irked by Miu’s mischief, subtle hints suggest she secretly enjoys the humor, upholding her "Straight Man" role against Miu’s "Wise Guy" antics. Similarly, she gently challenges Nobue’s carefree habits while remaining an engaged participant in group activities, reinforcing her stabilizing presence.

Her appearance—a dark brown single pigtail, brown eyes, and frequent blue attire—complements her practical demeanor, accentuated by a characteristically rough-edged voice. Throughout official media, her portrayal remains unwavering, consistently highlighting her role as the sensible, responsible core of her social dynamic.