In a void of nothingness, a single seed with immense power came into being. That being was named "Great Tree" - its branches spread out and created the Monsterra world. The five purest saps dripping from the Great Tree absorbed living materials and formed into five crystal entities called Soulcores. The Soulcores then hatched into mighty Mongens races, namely Celest, Chaos, Beast, Mystic, and Tectos. These magnificent creatures lived together to protect the spiritual sanctuary Monsterra for millenniums.
Life for all Mongens seemed to pass by peacefully. Until one day, an evil Chaos betrayed the Monsterra world, stole the powerful energy of the Great Tree to become the Supreme, and caused the Monsterra world to shatter into pieces. The Chaos sinner vanished into thin air while carrying the infinite power. Now, the long-lasting peace was gone, and the other Mongens had ceaselessly searched for the Great Tree's stolen energy source with the hope of retrieving the source one day.
Thousands of years passed by, humankind appeared. They exploited the floating islands, learned to live harmoniously with Mongens on the land, and made these creatures assist them to settle down. Human and Mongens joined efforts to exploit the land, expand the territory, enrich the living resources via farming, breeding, producing, and entering the battle with other lands to win the booty. The Mongens race has started a new life with humanity's assistance. But deep down, they still have a longing for their homeland to be merged someday!