Kyuruga is a domestic cat who arrived with Fuuta's younger sister when she moved in. His name stems from the distinctive pattern on his head being misread as a QR code by a smartphone camera. Initially unfamiliar with cats, Fuuta found Kyuruga bizarre, almost alien-like, but grew deeply attached over time.

Kyuruga displays classic feline traits. He frequently twists into improbable, unusual resting shapes reminiscent of objects like a roast turkey or a slug. Cardboard boxes and suitcases hold a powerful allure, drawing him inside, especially when humans pack or do chores. His reactions to everyday actions are unpredictable; sometimes mistaking them for play invitations.

Capturing his image proves difficult due to swift movements and a tendency to look away from cameras. Nevertheless, he becomes the frequent subject of photos taken by Fuuta, whose phone accumulates images of the cat. Kyuruga's moods shift rapidly. He engages in characteristic cat activities: scratching designated posts, seeking comfortable sleeping spots, and reacting to vet visits. His presence significantly shapes household routines, with humans adjusting their behavior for his comfort and preferences.

Later, additional cats named Chikuwa and Konbu join his social circle. Kyuruga's daily antics and needs become central to Fuuta's life, evolving from initial novelty into essential companionship. Fuuta catches himself unconsciously scanning rooms for Kyuruga or missing him during absences, underscoring the cat's integral role in the home. Kyuruga's actions remain consistently feline, with humor arising from the accurate portrayal of common cat mannerisms and the humans' adaptation to life with him.