Frankie Stein is a supporting character in the anime series 'Peach Boy Riverside.' He is a friendly and eccentric demi-human scientist who travels the world in pursuit of knowledge and invention. Despite his odd appearance and quirky personality, Frankie is skilled in mechanics and engineering, often assisting the protagonists with his technical expertise. His inventions and resourcefulness play a vital role in helping the group overcome obstacles throughout their journey, making him an indispensable ally and a source of comic relief within the story.