Maru is a cat Pokepi character in the Doko Demo Issyo series, who is Toro's drawing of himself brought to life after he drew in a magic sketchbook in an episode of Mainichi Issho.
They were used mainly to create merchandise, but there are also official renders of them made which are shown in one episode of Mainichi Issho. They resemble Toro, but smaller, with crudely drawn eyes, and a similarly crudely drawn mouth.
A plush of Maru