Prologue A - Origin of the Digital World
Author's Note: I do not own Digimon or the "cameo characters" that will appear in this series. I do not own the .hack-ish properties this story contains, but merely inspired by it. I own the characters created just for this story.
According to the video game Brave Tamer, the Digital World's beginnings can be traced to the early twentieth century, with the activation of the Atanasoff–Berry Computer (ABC) - the first computer - which laid the basic foundations of the world. Subsequently, the first patented computer, ENIAC, was activated, and proceeded to build upon those foundations, shaping the Digital World. Over the ensuing years, through the continued growth of the electronic communications network on Earth, the Digital World continued to expand and grow, even after the ABC and ENIAC were shut down. There are multiple alternate reality incarnations of the Digital World, each one running parallel with the various multiple Earths that exist in the multiverse.
The different Digimon anime series are set in separate Digital Worlds. The basic mechanics, locations and inhabitants of Digital World appear in each, though the individual natures, origins, and histories of the worlds vary greatly. Similarities between the various Digital Worlds exist, however. They all basically parallel Earth's geographic features. There are continents, islands, deserts, mountains, oceans and almost all other kinds of terrain one finds on the topography of Earth. However, as data is easy to modify, and considering that the Digital World is made up of data, the features of any particular area of Digital World are subject to immediate and drastic alteration at any time. For example, a gigantic mountain can be formed in moments or halves of islands can be scattered across a sea with ease. The malleability of the Digital World makes it a frequent target of attack from within and from humans with malevolent intentions.
Although ordinary animals like birds and fish are known to exist in at least some of the Digital Worlds, the dominant lifeforms of all realities are Digimon. Digimon are sentient creatures that, like the Digital World, are made of data. It is possible for Digimon to travel to the "Real World," what Digimon call Earth, though this requires the opening of some sort of dimensional wormhole in Digital World.
Most of humanity does not know of Digital World's existence. The few humans that do either programmed some aspect of the original version of that world or were summoned there by a Digimon or another digital being. On rare occasions, however, a wormhole can appear on Earth, allowing people unknowing of Digital World to enter it.
Prologue B - The Story of Yggdrasil
During the beginning of the Digital World, there released a virus known as the X-Virus, an ancient form of the virus today. The super computer being known as Yggdrasil decided to wipe out the over populated Digital World by wiping out all Digimon infected by this Virus. In the end, he planned to destroy this world and make a new one, bringing only a small percent of the Digimon. Dorumon was one of those who contained the X-Antibody, but was rejected by the other Digimon. Those with the X-Antibody were those not chosen by Yggdrasil, but survived. The X Digimon and the normal were in chaos with each other, but the X Digimon were mercilessly being destroyed by Yggdrasil's Royal Knights, mostly Omegamon.
At times, Dorumon was targeted by this Royal Knight, but Dukemon, Omegamon's close friend, knew that Yggdrasil was wrong, and those with the X-Antibody weren't meant to die this way. In the end, Dukemon sacrificed himself to save Dorumon. Dorumon underwent his Digivolution into Dorugamon and fled, soon being found by a few refugee Digimon. But a copy of him, DexDorugoramon, had spawned many DexDorugreymon to attack the refugees and destroy Dorumon to implement Yggdrasil's Project Ark, the plan to erase all Digimon.
Dorugamon underwent another evolution, becoming Dorugreymon. He was supported by WarGreymon X, MetalGarurumon X, and the former Royal Knight, Dukemon X, who allowed him to see Yggdrasil up in the heavens. But he ended up fighting with Omegamon. Almost nearly been killed, Dorugreymon digivolved into his final form, Alphamon, the TRUE leader of the Royal Knights. He ended his farce with Omegamon, telling him that this wasn't the answer. he got the Royal Knight to agree, and the two set out to confront Yggdrasil.
But instead, they found DexDorugoramon. Thought they had a hard time, the Death-X Digimon was destroyed to bits. Once the two Royal Knights found the host computer, DexDorugoramon reformed into Death-X-mon. The Digimon, which became the source of the X Virus, was Alphamon's shadow, and won't be destroyed unless Alphamon was killed in the process. Alphamon gave Omegamon his X-Antibody after he killed the virus and himself, the two merging together into one entity. Omegamon proceeded to Yggdrasil and destroyed it. As a result, the Digital World resetted. Omegamon X and Dukemon X became the new guardians of this world, waiting for Yggdrasil's rebirth.
Years later, Yggdrasil was reborned, his eyes opened by Alphamon. But as long as Dorumon, or Alphamon, existed, the virus would continue to exist. So it was decided by him and the rest of the Royal Knights that Alphamon would be sealed inside the Holy Capital resting on ElDoradimon's back. With that, the virus was sealed. Or so they thought.
A dark god, one of Yggdrasil's most abominable creations, wanted this virus released, and created the Dark Crests to further it.
Years before Tai and the others, around the year 1994, a high-schooler named Ueda Kaito had disappeared from the face of the Earth. Some believed him to be dead. But in reality, Kaito was the first human to ever discover the Digital World.
He met Leormon, his Digimon partner, and traveled this new world with him. In time, he grew fond of it, wanting to stay here forever. But it was fate that he and Gennai met, under the workings of Yggdrasil. Yggdrasil deemed Kaito worthy as the first Digidestine and asked the human to destroy a powerful evil God that created the 7 Dark Crests that opposed the Crests of Light. Yggdrasil scattered the Crests of Light to prevent them from falling into the evil hands of the god known as Milleniumon. Kaito and Leormon ventured into the Digital World, collecting the seven Crests of Light. Finding the Crests of Courage, Friendship, Knowledge, Love, Sincerity, Reliability, and Hope, the seven good aspects of a human, involved the creation of the Crest of Light.
But Kaito and Leormon hadn't finished their mission. They battled an evil human named Watanuki Hyuuga, and his partner created especially by Milleniumon, Arkadimon, brought to this world by the dark god to oppose Yggdrasil's Digidestine of Light. Their encounters increased until the end, and Hyuuga was ultimately defeated by the light. When Kaito and BanchouLeomon defeated Milleniumon, the god split itself into two beings; Kimeramon and Machinedramon, and retreated.
(Ultimately, in the Wonderswan Games, Ryo Akiyama destroyed Milleniumon all together, resulting in the crossing of dimensions with his digimon, Cyberdramon, who is said to be a part of Milleniumon. Therefore, Ryo succeeded where Kaito failed.)
But the battle cost Kaito most of his energy. If he returned to the human world, he'd surely die. Knowing his time was drawing near, he offered his body to Yggdrasil, telling him that he would spend the rest of his days in the Digital World. In time, he died, and the Digimon God Yggdrasil had entered Kaito's body, and lasted for many years to this very day. Even now, Yggdrasil still prays for Kaito's bravery, and still regrets ever making such a young child fight a dangerous battle that ended up costing the boy his life.