Miwa Yamada, known as Mom, is the human matriarch of the Yamada family. She found Chi as a lost kitten during a walk with her son Yohei. Initially trying to find the kitten a new home due to apartment pet restrictions, Miwa ultimately decided to keep Chi when rehoming failed, navigating this challenge with compassion and practicality.

Her daily life centers on caring for Yohei and Chi as a housewife, maintaining the household routines underpinning their family life. She participates in pivotal moments involving Chi, including facilitating the kitten's reunion with her biological mother, Marie, after Marie was injured saving Chi from a car accident. This led to Chi temporarily staying with Marie's family, though Miwa later supported Chi's choice to permanently return to the Yamadas when Marie offered it.

When the Yamada family planned a trip to Okinawa for her husband's work, Miwa was involved in the decision to bring Chi along, continuing her role in integrating the kitten into family activities and transitions. Her relationships focus on her immediate family: she is wife to Kento Yamada and mother to Yohei, both sharing affection for Chi as their pet and family member. Miwa also interacted indirectly with Marie during Chi's temporary stay, cooperating in the kitten's care during that transition.