Brought to the modern day by a group of alien invaders who were intending to conquer Earth, the creature was genetically altered by the aliens - who augmented it with the DNA of both the mutated dinosaur Godzilla and the alien dragon King Ghidorah. Placed under their mind control, the ancient beast underwent a metamorphosis as its body reacted to the augmentation of Godzilla and King Ghidorah's DNA. This resulted in the creature violently emerging from its 'cocoon' as one of the strongest monsters on the planet. Bagan's true form before his genetic augmentation is never shown.