According to legend, the peaceful Pluster World fell into chaos with the appearance of the Minusters, and in response, all of the Plusters fought alongside the humans, or, more specifically, merging with them in order to become more powerful ("plusting"), and were able to seal away the evil Minusters. Or so they thought..
The resulting peace was thought to continue forever, with the world once again returning to fruition, but the peace has ben shattered again by the reappearance of the Minusters.
Beetma, a Pluster from the Kabuto Tribe, on a journey to become the most powerful Pluster, meets up with Wyburst from the Grip Tribe, as well as a Minus-Beast. Completely overmatched in battle, Beetma accidentally finds himself sent to the world of humans, where he meets an 11 year old boy named Tohma, hoping for revenge on the Minus-Beast. Wyburst, looking for the legendary Gonggorahgong (which will bring peace to Pluster World) eventually joins them on their quest to defeat the Minusters as they meet many other Plusters and journey onward.