It all starts with Ryu Rider, who accepts a pact with Beryllmon, a demon disguised as a Digimon. Together they go on adventures, getting Beryllmon stronger and obtaining new powers. Once he got godlike status, he gave Ryu his one wish as a promise to the pact. After wishing to be Flint Baron/his existence, Ryu was attacked by Beryllmon, infecting his right arm with demonic beryllium poisoning. Sent back to Earth, Ryu Rider grows up and becomes Fang Ferro. The he uses the infected as a weapon to fend off the new threats that came along with his wish. His life of being a mercenary deteriorates as the infection caused him to fall into a coma, resulting in the manifestation of Pierre. As a way to keep himself sane, Pierre creates Gyero and Rototo, as memories of his best friend. In a certain timeline where Fang never wakes up from his coma, machine has taken over the world, with the main supercomputer attempting to eradicate the last humans. Since the settlements are hidden with magic, dragons were raised using appliances. Camera contains the soul of Fang Ferro, yet he never finds out after being transplanted.
And uh, Aremac is Camera's adopted brother