Life Stream Dragon was fatally injured in the final battle of the Nazca War. When the Earthbound Gods were sealed in the geoglyphs through the Crimson Dragon’s power and Uru dragged Ancient Fairy Dragon into the spider geoglyph with it, Life Stream was the one to fly after them and attempt to free her where all the others were in shock. He nearly succeeded in severing Uru’s webbing, and would have done had it not been for the interference of the Underworld King.When the Underworld King arose, it separated Life Stream from the others and beat him to the brink of death, severing his right arm at the elbow in the attack. Although the other Signer Dragons succeeded in beating the King back into the Underworld for another 5000 years, they did not know what became of Life Stream. The Crimson Dragon found him dying some considerable distance away from the others and altered his spirit into a mechanical form known as Power Tool Dragon, essentially putting the spirit on life support to prevent any more casualties in the Nazca War. In doing this, Life Stream’s genetic makeup was wholly altered, replacing his lost arm with a mechanical replacement. It also resulted in Ruka, along with any other spirit-sensitive duelist being unable to sense the truth behind Power Tool being the fifth Signer Dragon and the fact that Life Stream was not simply clad in armour with his true form being beneath it. Life Stream was not clad in armour, he became the armour, as seen when Power Tool’s joints show only black emptiness beyond the metal and not actual flesh.
However, in order to maintain this life support until such time as a befitting fifth Signer awoke or Life Stream was sufficiently healed, the Crimson Dragon also wiped all evidence of Life Stream Dragon from the memories of every spirit, including Life Stream himself:
the Signer Dragons remembered only a fifth dragon being in the battle, but nothing of their name or what they looked like to describe for the future Signers’ benefit.
all Life Stream’s memories were erased until the point of his resurrection as Power Tool Dragon, with his mind being programmed to assume he was only brought into creation after the war or has simply forgotten over time what his role was in the war.
The brother-sister relationship between Life Stream and Ancient Fairy was transposed onto Power Tool, with Power Tool believing he had been in the place of Life Stream the whole time.
All other duel spirits only remember there being five dragons and can only describe Stardust, Red Demon’s, Ancient Fairy, and Black Rose sufficiently. Like the Signer Dragons, they only remember a fifth being there, and any attempt to recall beyond this is a fruitless effort.
As they were sealed within the Nazca geoglyphs at the time, the Crimson Dragon’s memory wipe was not as effective on the Earthbound Gods. They clearly remember an orange-coloured fifth dragon being there and, although they cannot recall whether it was him or not, all of them have the distinct impression there is something incredibly familiar about Power Tool Dragon.
Life Stream’s memories, along with all other Signer Dragons and duel spirits, were returned the moment Rua ascended to become the sixth Signer and unlocked his true form. He still clearly remembers his time as Power Tool Dragon, and as such develops an identity crisis he hides from all the other dragons and Signers. Who is he? Is he Power Tool Dragon, or is he Life Stream Dragon?