A talking hippo in a neon-green "P" shirt tries to stay inconspicuous. The absurdity is the point, and the movie commits to it completely, treating a ridiculous premise with enough genuine heart that you're rooting for Potomas to escape capture, not laughing at him. Kids who stumble onto this discover something 80s anime rarely does: pure, uncomplicated adventure where the hero's biggest handicap is his own visibility.

Potomas is a hippo with a remarkable secret: he can talk just like a person. Only two young children, Maki and Toshi, are aware of it. He goes about in a bright green T-shirt marked with a huge letter "P", an outfit that is meant to help him avoid notice. Things go wrong when Potomas rescues a child from drowning and, for a moment, forgets to stay silent, speaking to the kid he just saved. Stories about a hippo that talks start circulating, and Potomas has to flee.