Mitsu and Itsuki run a peculiar business in the Kaminazaka district of Tokyo: they are bond cutters, able to see the physical manifestation of the connections between people and, for a fee, sever those that have become rotten or toxic. Mitsu is the one who perceives these bonds, while Itsuki, a tall and composed man, acts as her partner. Together, they take on clients entangled in relationships that have soured beyond repair. Their cases range from a client clinging desperately to a controlling lover to the aftermath of infidelity, from a corrosive friendship rooted in the past to a tangled situation involving both bond-making and bond-cutting. Each assignment exposes the hidden truths and messy emotions beneath the surface of human connections.

The pair’s own history is deeply intertwined. Both were born in a remote village where most inhabitants made their living through some form of bond-related work. Mitsu was considered an oddity there, and when she was young, her own parents severed their bond with her, leaving her with only her connection to Itsuki. That shared past and the only bond that remains for her drive much of the story, as the present-day episodes gradually reveal the loneliness and resilience behind their profession. The series weaves together standalone cases with the unfolding mystery of how Mitsu and Itsuki came to be and what it truly means for a bond to be cut.