Chika is the younger sister of Sae, a main character in the Hidamari Sketch series. She is typically in her third year of middle school when she is first introduced, making her about thirteen years old. Chika is portrayed as being more spontaneous and energetic than her older sister, with a lively personality that visibly contrasts with Sae's more reserved and studious nature. Despite these surface differences, she shares a core of pride and stubbornness with Sae, which often leads to verbal sparring or arguments whenever they interact. This sibling dynamic is a key aspect of her character; their conversations frequently degenerate into fights, yet it is clear they are on good terms and care for each other deeply beneath their competitive exterior. One notable example of this hidden affection is when Sae strokes her sleeping sister's hair after a disagreement.

Chika harbors a longing for the high school life and has applied for a normal academic course, a different path from the art-focused track of her sister and the residents of the Hidamari Apartments. She enjoys cooking and has an infatuation with a kabuki actor, interests that distinguish her from the artistically inclined main cast. True to her preference for music and home economics over art, she demonstrates no particular artistic talent. In the story, Chika often serves as a visitor from outside Sae's immediate social circle, typically arriving to convey messages from their parents or to bring news, such as Sae's test exam results. Her presence helps to explore Sae's familial relationships and adds another layer to the series' focus on friendship and personal growth.

Her role becomes more prominent in later seasons, particularly in Hidamari Sketch × Honeycomb, where a visit from her leads to a significant development in her relationship with Sae. During this visit, she questions Sae's choice of colleges, expressing concern that Sae is prioritizing the family's finances over her own well-being, which reveals a more thoughtful and caring side to her personality. Over the course of the series, Chika develops key relationships with the other residents of the Hidamari Apartments. She quickly forms friendships with the younger characters, Nori and Nazuna, due to their proximity in age, and is shown enjoying activities like having gyoza parties and playing board games with the entire group. Her willingness to interact with them, such as asking to see their rooms, helps her integrate into Sae's world, showing a clear progression from a distant relative to a more integrated part of the extended social circle.