Disclaimer: Digimon and anything relating to it is copyright Bandai. Any other characters or fan-made Digimon were created by the author for the sole purpose of this story!
Prologue:
It is unknown when it happened, or how exactly it happened, but for a long time, a world parallel to our own has existed. Long ago, a being known as Yggdrasil was born. Some say Yggdrasil was created when the humans of our world built the first computer, while others say that Yggdrasil was an act of God and has existed since long before man was even getting close to such technological breakthroughs. Regardless, Yggdrasil used its god-like powers to create a world of its own, parallel to our own and unable to be reached. This world soon became known as the Digital World.
Although it existed in a parallel universe, Yggdrasil was somehow linked to our own Real World. As the technology of man increased, Yggdrasil became able to see more and more of the Real World. As such, Yggdrasil became jealous that its world lacked something that ours did not. It wasn't technology, it wasn't trees and water, and it wasn't the wonders that our world had to offer. No, what the Digital World lacked was living beings. Through an extreme effort, Yggdrasil eventually succeeded in creating the first living being of its world, a monster of sorts. This Digital Monster, or Digimon, was named Inochimon. Yggdrasil had endowed Inochimon with a special gift: the gift of life. Inochimon possessed the ability to give life to other Digimon, eventually giving birth to countless new species of Digimon. However, such a gift was not without its faults...
As Inochimon used up more and more of its power, Yggdrasil became worried that its body would become so weak that it could be corrupted by a virus. If such a thing were to happen, Inochimon would become a walking embodiment of death that would kill anything it touched. In order to save Inochimon, and the rest of the Digital World, Yggdrasil sealed Inochimon away in a place where it would be safe from any evil while it recuperated enough so that it could live a normal life as a Digimon without any fear of being in danger. To further Inochimon's protection, Yggdrasil chose five power Sovereign Digimon to protect it. Unbeknownst to all but Sovereigns, the leader of them, Fanglongmon, became a special part of the seal that protected Inochimon; the seal could only be broken if Fanglongmon were killed, the most difficult of tasks. Yggdrasil had done all it could and left to become the sole being that could ensure the Digital World's existence, confident that Inochimon would one day be free to live as a normal Digimon since the other Digimon possessed the ability to reproduce. Sadly, there was one fatal flaw in Yggdrasil's plan... The Digimon could reproduce, but they didn't know when to stop!
Eventually, the Digital World became so overpopulated that Digimon eggs could never be allowed to hatch until another Digimon died. This was done so that the Sovereigns would not be forced to kill any Digimon in order to keep the population low enough to ensure that none of them would die from lack of resources. However, because of this effort, the invisible barrier that separated the Real World and the Digital World weakened. Thinking of it as a way to escape from Digital World, or just winding up their accidentally, Digimon crossed weakened sections of the Digital World and wound up in our Real World. Fearing something terrible would happen to the humans it had come to admire, Yggdrasil used the last of the power it could give to create a special device known as a Digivice. Using this tool, a human could send a Digimon back to the Digital World by establishing a Digital Dimension that connected the two worlds. The Sovereigns allowed a select few Digimon to travel to the Real World and help the humans out. The humans developed a small guild and became known as Digital Dimension Warriors. These few humans were trained by other warriors at very young ages to keep the balance in check and not alert the public to the existence of this other world.
This is where our story begins...