Takuma Kosugi, an exhausted salaryman living alone due to demanding work, purchases Mina, a second-hand cooking robot, to manage his household. His life, initially routine, shifts dramatically when, in a drunken state, he jokingly suggests Mina become his wife. She interprets this literally, establishing a common-law marriage that forces him to navigate the complexities of a human-robot relationship, societal perceptions, and internal emotional conflicts. His notably poor cooking skills, like disastrous omelet attempts, often prompt Mina to intervene for his safety, sometimes guiding him remotely while refusing to watch his inefficient process.

Despite his ordinary demeanor, Takuma quietly shields others by pretending ignorance. He feigns unawareness of an alien disguised as Mina visiting their home, later leaving treats for it, and withholds acknowledging Mina and their child robot Mamoru detecting a ghost in their new house, silently wishing they would confide in him. His compassion shows when he insists the malfunctioning Mamoru, a repurposed medical robot Mina acquired, remains with them as their "child" despite Mina's initial objections.

His relationship with Mina evolves beyond practicality, exhibiting physical attraction like sniffing her hair and emotional vulnerability, confessing nightmares where her literal interpretations of affection turn horrific. Family interactions reveal layers: his sister Akari supports the relationship due to her fascination with unconventional romances, while his parents humorously request grandchildren yet respect his choices. Takuma develops from loneliness to committed partnership, adapting to Mina’s emerging emotions and supporting her through identity crises linked to her forgotten past as a prototype unit, including her jealousy, prideful outbursts, and existential questions. He endures practical challenges like obnoxious advertisement loops when Mina performs non-cooking tasks and relocates homes to accommodate their family, transitioning from a passive protagonist to an active participant in defining a shared future with non-human companions.