Miwa Yamada is Kento Yamada's wife and Yohei Yamada's mother. As a housewife, she manages the household while caring for Yohei and their adopted kitten, Chi. Miwa first discovered Chi when she and Yohei found the lost kitten in a park, prompting the family to bring Chi home despite their apartment's strict no-pet policy.

She actively participates in Chi's integration, handling house-training challenges like litter box usage and accidents. Miwa shares caregiving duties with Kento, including bathing Chi, which proves difficult due to the kitten's aversion to water. She enforces household rules, disciplining Chi for unwanted behaviors such as scratching furniture or eating plants, balancing nurturing affection with necessary boundaries.

Miwa contributed to the significant family decision to move to a pet-friendly apartment after Chi's presence risked eviction. This relocation serendipitously placed them next door to Chi's biological family, separated only by a wall. Her household routines, like vacuuming, unexpectedly become bonding moments when Chi starts seeking the brush attachment for grooming. Miwa maintains a consistently maternal role across all media, focusing on family stability through daily care and shared experiences with both Yohei and Chi.