Though it is not known why or when, Realm 900 is entirely uninhabited. The reduced possibility of casualties is likely the reason the Chamber was built here.
40,000 CH BC
After Frank had made some serious slights toward Anime and the Weeaboo community in general, Salamander Man informed him that the Weeaboos had risen up and were coming for him. Frank and Pink Guy travelled to this realm to take shelter from the attack in the Weeaboo Protection Chamber. There, they were safe as the Chamber was thought to be impenetrable by even the most devout of otaku.
However, Weeaboo Jones, of Realm 9.12, was able to break through the protection of the chamber and a battle between he and Frank ensued. At first, it seemed as though Jones would win the fight but Frank was able to snatch victory from the jaws of defeat with a barrage of "Reality Checks."
The fate of Realm 900
It is actually unknown if SunCorp actually took over this realm, as Realm 900 contains the Weeaboo Protection Chamber, and so the Vegan Protection Chamber looks very similar to it, which is located in Realm 00000, another realm now privately owned by SunCorp. It is then suspected that they actually colonized the abandoned realm.