[@Inner Demon]

Alright. I'm gonna give you a detailed example of what I mean using the backstories of one of my characters:

So, we have Jason Troy, a human from our Earth. Normal Earth. No aliens, mutants, supers, robots, whatsoevers, just vanilla Earth. During the bombing of London (i.e. WWII), he wound up getting into a portal and ended up in another world. There, he gained a new power from it and some new ideals from the experience he had (namely, [s]terrorists[/s] "freedom fighters" ticked him off so much he resented ever being a member of them and resents being a hero and all the bells and whistles of it) and traveled the multiverse with that ideal in mind. 

So, your character is sort of that same line, at some point in Earth's timeline, a human, your character, ended up getting into a portal and winding up in another world. This world being your setting with the Cyber Beast. Makes sense?