Grandmother (Bāba) is Kun's maternal grandmother, appearing through his time-travel journeys and present-day family life. During Kun's trip to the past, he witnesses her childhood frustration with her own mother after being denied a pet cat. This sparks her minor rebellion: deliberately scattering toys and food throughout the house before facing discipline. Observing this scene helps Kun grasp that his own mother encountered similar childhood struggles and parental authority.

In the present, Grandmother connects Kun to his family's history by sharing photographs, including images of his mother as a child. These moments bridge past and present for Kun, though he initially finds reconciling these stories with his current frustrations difficult. She actively maintains family traditions, participating in Girls' Day (Hinamatsuri) celebrations for Mirai, but does not involve herself directly in the central conflict concerning the dolls' storage afterward.

Her background encompasses marriage into the family and raising Kun's mother. Her experiences as both a daughter and a parent underscore recurring themes of generational understanding and familial bonds.