Mifuyu Kishi lives in the Asagaya Apartments complex with the protagonist's family. She is the mother of Shingo Kishi, a fourth-grade elementary student and the protagonist's playmate, and Wako Kishi, a fifth-grade student. Her residence and family connections place her within the core group of residents tied to the extraterrestrial events centered on the apartment building.

She maintains a close association with the Sawatari family, primarily through the friendship between her son Shingo and their son Yuuma. This neighborly connection links her to the housing complex's social dynamics but does not involve her directly in the main narrative concerning the comet threat or the alien intelligence called The February Dawn.

Across all documented original manga, anime film, and related official media, Mifuyu Kishi exhibits no significant character arc, backstory exploration, or development. Her role remains consistently defined by her familial ties and presence as a resident. Information about her history prior to Asagaya Apartments, personal motivations, or any evolution beyond her supporting maternal role remains unspecified.