Tsuzuki Takumi is an Ordinary High School Student who lives with his older sister Otome. He along with his childhood friend Serizawa Fumino run a patisserie called "Stray Cats". The name is apt as his sister often brings back stray cats. The story begins when one day, instead of a cat, something unexpected is brought home! Mayoi Neko Overrun! is a light novel series authored by Matsu Tomohiro, with illustrations done by Peko. For its manga adaptation, Kentaro Yabuki (Black Cat, To Love Ru) does the art.