The Bydo were banished to another dimension where they evolved into a sentient embodiment of evil. They made this their home dimension ever since.
In R-Type III, the Bydo Dimension is in red space with the Bydo Core attached to a wall. In R-Type Delta, the Bydo Dimension is a twisted version of the Humans' dimension; There are giant strands of DNA, cities on the ceiling and floor, babies encased in crystals, images of science formulas and major human accomplishments in the background, and a forest of Bydo Trees. In R-Type Final, the Bydo Dimension is full of Bydo fluid with images of a couple making out in the background. It is also inhabited by Bydo eyeballs.