Chi, the youngest Matsumoto sister, exhibits a demanding demeanor that prompts her mother to humorously label her the household "CEO." Despite her extremely young age and fragmented speech—composed of broken Japanese structures and incomplete words reflecting early language development—she actively strives to participate in her older sisters Fuu and Suu's play scenarios. Her persistent eagerness to engage, undiminished by verbal limitations, frequently generates situational comedy within family dynamics.

Chi's role centers on her dogged attempts to join her sisters' activities, where her age and capabilities create natural obstacles. These interactions underscore the humorous challenges of a toddler navigating daily life alongside older children. Her portrayal remains consistent across all documented media, including the television series and 2019 movie adaptation, without significant character evolution, background exploration, or developmental milestones. Chi primarily reinforces the family's slice-of-life dynamic, highlighting parent-child relationships and realities of raising young children.