On a distant and embattled planet called Edenoi, a young prince named Dex is given great powers by his grandfather, the king, and is sent to the planet Earth to protect it from the advancing evil of Count Dregon and his vicious Insectivores. Once on Earth, he is adopted by a kind family and learns to live as a human. With his companion Ferbus by his side, Dex is ever vigilant. Ready at a moment's notice to call on his powers to become Masked Rider.