Kobato, a married woman with a young child, lives with her family at Toriai Mansion where her husband works as a doctor. As a new resident, she strives for neutrality by observing social conventions, introducing herself to influential figures like Mrs. Shiratori, the condominium management committee chairperson, despite warnings about conflicts. She also interacts with Mrs. Ukai, an elderly neighbor known as "The Witch," while intending to avoid the discord between Ukai and Shiratori.

Her involvement deepens upon encountering Mrs. Kamoshita, a visibly ill resident performing mandatory cleaning duties enforced by Shiratori. Driven by compassion, Kobato assists Kamoshita despite warnings of repercussions. This act draws her into direct conflict with Shiratori's faction, resulting in Kobato's unfair appointment to cleaning duty as retaliation. Shiratori and her followers systematically assign excessive tasks to pressure her into submission.

After Mrs. Ukai suffers a fall and is hospitalized, she entrusts Kobato with her mynah bird, Kyū, implying the bird might be useful. Kobato initially interprets this as temporary caretaking. Kyū frequently repeats the word "Kanishabu," which unsettles Shiratori during a confrontation, though Kobato doesn't grasp its significance. As harassment intensifies, Kobato begins actively resisting Shiratori's demands, refusing to apologize despite anonymous calls. Her resolve strengthens through shared hardships with Kamoshita, and they collaborate to challenge unreasonable directives, like insisting residents manage their own mailbox tidying.

Conflict escalates when Shiratori sabotages the communal trash site, disguising herself to mix categorized trash and demanding Kobato and Kamoshita clean the mess. In desperation, Kobato uses "Kanishabu" against Shiratori, but it fails. Ukai unexpectedly returns and reveals "Kanishabu" refers to a crab she once received, which escaped and was later found eaten by Shiratori—who suffered food poisoning. This revelation forces Shiratori to clean the trash herself to prevent public exposure. The ordeal concludes with Shiratori leaving the condominium, while Kobato, Ukai, and Kamoshita share a meal of crab. Kobato reflects that Ukai's true intent in lending Kyū was likely practical pet care rather than strategic aid.