In the year 2200, Japan has undergone a profound transformation. Due to a severe and prolonged decline in the human birth rate, the nation has become a land where cats now vastly outnumber people. This shift has resulted in a society where felines are fully integrated into every aspect of daily life, possessing the ability to talk, learn, work, and even hold strong opinions.

The story centers on the daily life of Sora, a high school girl navigating this unique world alongside her pet cat, Mugishima-san. True to their new place in society, Mugishima-san is not a typical, silent pet but a logical, argumentative, and somewhat know-it-all companion who constantly challenges Sora with his sharp wit and feline unpredictability. Their relationship is defined by a constant, good-natured bickering that forms the comedic core of the narrative.

The supporting cast includes other human and cat pairs, such as Sora’s friend Yume-chan and her cat Kinako, as well as Sora’s father and other quirky feline characters encountered in school and around town. The narrative unfolds in a lighthearted, episodic fashion typical of a four-panel manga, focusing on slice-of-life comedy rather than dystopian drama. It explores the absurdity and charm of a world where traffic signs are adorned with cat symbols, libraries are guarded by napping felines, and daily arguments with one's own pet are a routine part of life.