Iwaya Sumire is a highly accomplished woman in her late twenties who seems to have everything: a prestigious university education, a respected position as a journalist for a major newspaper, and striking good looks. Despite these advantages, her professional life takes a downturn when she is demoted after punching a superior who made unwanted advances, and her personal life crumbles when her long-term boyfriend ends their relationship. On a particularly devastating evening, while returning home drunk and heartbroken, Sumire discovers a young homeless man sleeping in a large cardboard box outside her apartment building where she had expected to find a puppy. Mistaking the disheveled but beautiful stranger for her beloved childhood pet, she impulsively offers to take him home.

The young man, a twenty-year-old modern dancer named Takeshi Goda who has been injured and is without a place to stay, surprisingly accepts her strange proposition. Sumire establishes an unconventional living arrangement: Takeshi may live in her apartment, but only under the complete condition of becoming her pet. She renames him Momo after her former dog, and he agrees to behave as such, staying home, waiting for her return, and providing unconditional physical affection without the complications of a human relationship. For Sumire, who has grown weary of the pressures and disappointments of conventional dating, having a pet who cannot speak back or make demands feels like the perfect solution.

This unusual dynamic is tested when Shigehito Hasumi, a former boyfriend from nine years earlier for whom Sumire still carries strong feelings, reenters her life and shows renewed interest in her. The return of this seemingly perfect romantic prospect forces Sumire to confront what she truly wants. Simultaneously, the boundaries of the pet arrangement begin to blur as Takeshi starts demanding more attention and the emotional bond between them deepens. As Sumire navigates the contrast between the socially acceptable relationship with Hasumi and the secret, tender, but strange domestic life she shares with Takeshi, she must decide what kind of love she is actually seeking. Her journey involves reconciling her public image as a strong, independent career woman with her private need for comfort and acceptance, ultimately learning that the most fulfilling connection might come from the most unexpected place. The story unfolds across the backdrop of Sumire’s competitive newsroom, the elegant but stifling dates with her ex-boyfriend, and the intimate sanctuary of her apartment where her true self is allowed to simply exist.