The Byrum appears as a clan of outer-dimensional nobles, who conquered many worlds in the Back Dimension, and are now moving on to Front Dimension, ours. They boast on being gods, while they despise humans and see them as stupid and worthless. Their base of operations was the Giant Demon Castle Vylock, a brain-shaped castle capable of traversing dimensions and sending its forces to Earth due to its Dimensional Transfer Machine. Upon arriving, they first destroyed Earth Ship, to prove their strength. In doing so, they gained a new member to their group, but also caused the Birdonic Waves energy to be released, striking four random humans on Earth, causing them to become Jetmen. First, they released a Dimensional Bug Mother, who fed on humans, growing its egg sack, so the Byrum could gain dimensional bugs to create Dimension Beasts. Seeing the Jetmen who would oppose them, the four leading members decided to make a game that whoever defeated the Jetmen would get the honor of being full-leadership. The, long thought dead, Empress of the Byrum, Juuza, returns to take command, causing suffering to Earth which would feed the Semimaru egg she acquired.