Kaijo are a race of creatures that apparently had their origin in Neo-Tristram, as the city's government utilized nuclear power. The scientists of Tristram Labs had grown overconfident. They believed the power of the atom was finally under their control. They were wrong.
A number of heroes are from the universe associated with the kaijo.
- The Defense mecha Cyb'arak designed by Frozen Throne technologies has proven instrumental in the defense of the African continent against the Kaijo monsters.
- Zerus-class mech D3-H4K4 was developed to gather Kaijo DNA mid-combat. Troublingly, the onboard AI has begun rejecting orders, extracting "essence" from its own targets.
- The Kaijo Diablo could not be contained; cities worldwide had been reduced to cinders. Now humanity's survival hangs upon the untested mecha, Tassadar.
- "Kaijo" is likely a pun on kaiju, a type of creature found in Japanese monster films.