Lore: there was one factory where it makes slime with every single colour, one co-worker who was lately a A.I creator, he thought of using his electronic skills on the slime to make them real. He uses light-blue slime to test, couple hours later he completed his creation. It was 1am on that time so he went to sleep fast. Then next morning, the creation was gone.
Extension: before being in the bossfight world, he trained his powers & created his own friends,