Bem, Bella and Bello are ugly monsters that are neither human nor animals, but they are peace-loving, righteous heroes who feel compelled to help humans in trouble. Because they are monsters, they are feared and detested by humans, and on top of that, pursued by the police. However, a friendship develops between them and a detective by mere accident. Through their contact with humans, Bem, Bella and Bello's earnest wish to become human grow increasingly stronger. They battle evil for the sake of mankind, in the belief that they will be able to become humans one day.