A white ermine, known in Japan as an okojo, Okojo-san lives at an exotic pet store run by a greedy manager until one day he escapes. In the chaos following, he ends up unconscious in a garbage can, where college student Haruka Tsuchiya finds him. Mistaking him for a ferret, Tsuchiya takes Okojo home with him. At the Shiawase apartment complex, Okojo meets other pets, including the gerbil Chorori, and the various eccentric human tenants. With his friends, Okojo struggles to adapt to life with humans, vacuum cleaners, and all the other things that come with human society. The comedy is largely reliant on absurdity and Okojo's tendency towards melodrama.