The story begins with Sato, a tired office worker, leaving work on a Wednesday evening. His colleague, Sakakibara, expresses concern about his exhausted appearance, which Sato dismisses. As Sato heads home, a sudden snowstorm has blanketed the area. He stops at a convenience store for groceries and, while walking down a quiet, dimly lit rural road, hears a faint sound. Following the noise, he discovers a small, shivering white kitten in a cardboard box in an alleyway. Driven by an impulse, Sato rescues the kitten, wrapping it in his scarf and blanket.
Upon arriving at his pet-friendly apartment, Sato immediately sets up a warm environment for the kitten, turning up the heat and using a cushion. He begins to worry about the responsibility of caring for a pet, having never owned one before, and contemplates whether to take it to a shelter. However, he feels a strong resistance to parting with the kitten. He asks the kitten what it wants, and the kitten responds with a meow and a lick, which Sato interprets as a sign to keep it, at least for a while. This marks the beginning of their cohabitation.
The next morning, Sato wakes up to find the kitten, now named Mashiro, alert and watching him. Mashiro is initially wary but eventually eats the food Sato provides. Sato leaves for work, concerned about leaving Mashiro alone, but is reassured by the kitten's apparent well-being. At work, Sato is distracted by thoughts of Mashiro, even during lunch with Sakakibara, to whom he reveals he's adopted a kitten. Sakakibara offers advice and support, mentioning his girlfriend Ayano's experience with cats.
Over the following days, Sato buys essential supplies for Mashiro. He also informs his landlord, who is understanding and allows him to keep the kitten. Sato resolves to be a good owner, despite his anxieties. He finds joy in Mashiro's presence, observing its habits and even setting up a TV for it to watch while he's at work. Mashiro quickly adapts to the TV, showing a preference for calmer programs.
Sato also begins to notice Mashiro's intelligence and responsiveness. Mashiro starts to anticipate Sato's actions, such as waiting for him to eat before eating itself. This deepens Sato's affection and sense of responsibility. He buys Mashiro a comfortable new bed after seeing a commercial for one, and Mashiro seems to approve, sleeping soundly in it.
Their bond continues to grow. Mashiro begins to respond to its name and allows Sato to pet it without immediate escape. Sato also notices Mashiro's interest in nature programs on TV, which makes him wonder if Mashiro desires to go outside. He grapples with the idea of letting Mashiro experience the outdoors, balancing his desire to fulfill Mashiro's potential wishes with the risks involved.
One day, Mashiro sleeps on Sato's bed, forcing Sato to sleep on the sofa. This incident, while inconvenient for Sato, is interpreted as a sign of Mashiro's growing comfort in the apartment. Sato continues to spoil Mashiro, buying it salmon sashimi and other treats, and even considering a large cat tower, though space is limited. He finds immense satisfaction in Mashiro's happiness and the improvement in his own life, including a healthier diet and a renewed interest in reading. The narrative concludes with Sato reflecting on his deepening bond with Mashiro, finding fulfillment in their shared life.
