A year has passed since the final battle with Moo, Genki still cannot forget his friends. Suddenly he is led by an image of Mocchi to a deserted shop with a Monster Rancher game disc. Playing the disc he sees his friends quest to defeat Moo unfolds before him and saw what happened in his absence. After the battle, the gang is seperated. After finding and unlocking Mocchi from his Mystery Disc, Holly and Mocchi embarked on a quest to reunite the gang. They found a Mystery Disc containing Moo and Holly's father. Baddies reappear to claim the disc and the duo are in danger with Mocchi losing all his fighting abilities when he was turned into a Mystery Disc after the final battle with Moo. Also, a mysterious enemy seems to be behind the baddies.
