Yasuko Kusakabe is the wife of Tatsuo Kusakabe and mother to Satsuki and Mei. Her hospitalization for tuberculosis necessitates the family's move to a rural house near her hospital in postwar Japan, facilitating visits during her recovery.

She embodies warmth and maternal care. During hospital visits, she expresses affection physically, like brushing Satsuki's hair while noting their resemblance. Yasuko engages with her daughters' tales of household spirits, responding with playful encouragement rather than doubt. Though physically absent for much of the story, her emotional presence endures through letters read aloud and her concern for the girls' well-being during health scares.

Physically, Yasuko has brown eyes and dark brown hair typically tied in a low ponytail. She appears mostly in hospital attire, though epilogue scenes show her recovered, wearing traditional clothing like a blue kimono or dress. Her illness sometimes causes setbacks, such as postponed visits due to minor colds, distressing her children. A pivotal moment occurs when she discovers an ear of corn labeled "For Mommy" on her windowsill, coinciding with her intuitive remark about glimpsing the girls nearby.

Key relationships define her role: a supportive marriage with the frequently visiting Tatsuo, who updates her on family matters, and a central bond with Satsuki and Mei, who are deeply affected by her absence yet motivated by her return. Community ties include Granny, who assists the family.

The narrative concludes with Yasuko's hospital discharge. Reunited visibly healthier with her family during the credits sequence, her return home signifies restored familial stability. Supplemental media, like the short film *Mei and the Kittenbus*, references her without a physical appearance. No other official seasons, films, or spin-offs expand her background or development beyond this storyline.