Chika Itoh, full name 伊藤 千佳, acts as the "straight man" in her friend group due to her grounded and ordinary nature. Her older sister Nobue explicitly identifies her distinguishing trait as a complete lack of distinguishing traits, labeling her stereotypically average. Twelve years old and in sixth grade, she attends school alongside her neighbor and best friend Miu Matsuoka. Chika resides in the same apartment building as Nobue and Miu, with Miu frequently entering Chika's room unannounced via the adjacent rooftop. Her birthday is May 11 and her blood type is A.

Chika possesses dark brown hair typically tied in a single pigtail and brown eyes. She favors blue clothing.

Personality-wise, Chika exhibits greater common sense and practicality than her peers. Maintaining a cheerful demeanor, she displays seriousness about responsibilities, especially her studies. This focus leads her to prioritize homework over play, causing Miu to call her "uptight" for refusing to share answers. Her fiscal responsibility manifests as reluctance to spend money on treats during walks home, earning Miu's "cheapskate" remark. Despite this, she willingly bakes cookies and prepares treats for the group upon request. The meaning of her name, "thousands of skills," hints at versatility, with cooking emerging as her most recognized skill.

Her primary role involves reacting to others' eccentricities, specifically serving as straight man to Miu's unpredictable antics. Though often exasperated by Miu's behavior, she privately finds some pranks amusing. She similarly tolerates Nobue's frequent requests to borrow money for cigarettes. While generally patient, she demonstrates occasional sarcasm, like predicting Miu's "deranged" logic.

Relationships define much of her interactions. With Nobue, she shares a sibling dynamic where Nobue borrows money and teases her; Chika rarely receives the protective attention Nobue shows younger friends like Matsuri or Ana. Her bond with Miu is complex; despite constant pranks and insults, they maintain a childhood friendship where Miu deeply admires her. Miu ensures Chika's light is off before sleeping and considers Chika her "one and only." Chika shares a class with Miu and interacts frequently with Matsuri Sakuragi and Ana Coppola, both one grade below her.

Chika's background story remains consistent across media, with no significant development arcs detailed. She functions as an anchor of normalcy amidst the group's whimsy, her "generic" persona serving as a deliberate narrative counterpoint.