Tsushima, a brown tabby cat with the ability to speak human language, was once a stray scavenging through garbage bins until an elderly woman discovered and adopted him. His name derives from a superficial resemblance to the "Tsushima cat" breed, though he shares few traits with it.

He lives comfortably with his rescuer alongside three feline housemates: Miss Zun, the eldest and most authoritative; Cha, a skittish younger cat; and Osamu, a neighborhood stray who visits intermittently. Tsushima displays laziness and gluttony, frequently demanding food. Despite his caretaker's aversion to insects, he harbors extensive knowledge about them.