Set in a world where humans and monsters coexist, people who slay monsters are called Monster Hunters, whereas those who tame and live in harmony with monsters are called Monster Riders. Using a special stone, they form strong bond with monsters and ride on them across the vast lands. The protagonist Ryuto is a 12-year-old boy who lives in a riders' village called Hakumu Village and dreams of becoming the world's best Monster Rider someday. One day, he goes into a forest along with his buddies to find his own monster. As they proceed deeper, Ryuto miraculously encounters a monster named Rioraus. Then, an extraordinary story of their unforgettably thrilling adventure begins!