Chika Ito is a pragmatic 12-year-old sixth-grader, the younger sister of Nobue Ito. She shares her classroom with her neighbor and best friend, Miu Matsuoka. Chika has dark brown hair usually worn in a single pigtail and brown eyes, favoring blue clothing.

Nobue describes Chika as having a "complete lack of distinguishing traits," positioning her as the group's "straight man" due to her realism, pragmatic attitude, and frequent focus on homework. This practicality leads others, especially Miu, to sometimes see her as uninteresting or uptight; Miu specifically calls her "uptight" for refusing to play or share homework and a "cheapskate" for skipping treats on their walk home. Despite this, Chika is fundamentally cheerful and exhibits greater common sense than her peers, often acting as the only sane figure amidst their eccentricity.

Her dynamic with Miu is a classic "straight man and wise guy" pairing, with Miu's absurd behavior contrasting sharply against Chika's grounded reactions. Miu frequently disrupts Chika's studies by climbing uninvited into her room via the adjacent rooftop. Though Chika outwardly resists Miu's antics, she privately finds some amusing. She is skilled in cooking and baking, particularly cookies, and regularly prepares treats for the group, a role she generally accepts willingly.

Chika's development includes moments of vulnerability, like discovering she gained weight and attempting a diet after Miu's provocation. Her self-confidence was restored following a remark from Nobue. She occasionally breaks the fourth wall in early manga chapters, addressing readers directly about her frustrations. Her birthday is May 11, and her blood type is A.