Rika Kuroki is a 28-year-old single woman who has long given up on falling in love or getting married. She feels lonely living alone but cannot bring herself to love anyone. When her housemate and close friend Mio moves out to get married, Rika becomes frightened of growing old by herself and decides to adopt a rescue cat. At the cat adoption event, however, she is told that single people are not permitted to adopt a cat because there would be no backup caretaker in an emergency. While drowning her disappointment at a nearby bar, she meets a man named Sasagawa, who is in the same situation—single, lonely, and desperately wanting a cat but barred from adopting. The two make an unusual pact: they will move in together and share responsibility for the cats. This arrangement lets them adopt two shelter cats, and what begins as a practical solution slowly turns into a quiet, unassuming cohabitation.

The story follows Rika and Sasagawa as they navigate the daily rhythms of living together with their two feline companions. Both are emotionally guarded and have complicated relationships with love and intimacy; Rika has never experienced romantic attraction, and Sasagawa is similarly wary. Their shared care for the cats becomes a gentle foundation for mutual trust. The narrative explores themes of loneliness, chosen family, and the idea that cats perceive humans as simply “big cats”—other beings to live alongside without the pressure of romantic or social expectations.

As the series progresses, old relationships resurface. Mio, Rika’s former housemate, returns after a failed marriage and briefly moves back in, creating tension and forcing Rika to confront her own feelings about independence and connection. Meanwhile, a man named Ozaki, whom Rika once dated, reappears, revealing that she does have some capacity for romance—a revelation that unsettles Sasagawa. He worries that he is standing in the way of Rika’s potential happiness. In the final volume, Rika must decide whether to pursue a conventional romantic relationship with Ozaki or to continue her peaceful, cat-centric life with Sasagawa. She ultimately chooses the latter, embracing the philosophy that she and Sasagawa are simply “big cats” who have found their own kind of contentment—a home built not on passion, but on quiet companionship and the warmth of shared solitude. The manga concludes with the two humans and two cats settling into a stable, unorthodox family unit, having grown into the people—and the cats—they always wanted to be.