A trading card RPG based on the Monster Rancher franchise.

Before the world's continents broke up into pieces, a huge disaster hit the world. People prayed to God for help, and God created new life forms. However, new life forms brought new troubles, so God became exasperated and sealed them in "disc stones". Many years have passed since then and God entrusted the humans with the secret of "disc stones". Today people still continue searching for these missing "disc stones" to unlock the lifeforms within. In the anime, the monsters were created by scientists.

It is said that one monster is trapped inside each one. One day a group of workers excavating the ancient ruins happened to dig up one of these mythical disc stones. The worker who first discovered a disc stone took the disc to the Monsters' Temple. There the priests, using the ancient methods, unlocked the monster inside the disc stone. In a place where ranchers and monsters coexisted peacefully, the battle of the monsters began. As time passed these monster battles became extremely popular, and monster breeding became the standard pastime of the land. Eventually disc stones were found around the entire world. Now ranchers across the globe come together and enter unto battle.