This is a world where both men and monsters exist. Those who hunt the monsters are called Hunters. But in a small corner of the Hunter�s world, there are those called Riders who bond with and coexist with monsters. With their Kizuna Ishi (Bonding Stones) that allow them to awaken the hidden power inside monsters, Riders live in secrecy together with their Otomon, the monsters they formed a connection with.