From The Heretic Knowledge Vault
|Location:||Somewhere off the coast of Tsuiraku|
The Rinkai's skills in building and enchanting made the creation of Malacia a singular feat. In essence, it was a floating city (one very large building). Flying at a height of a kilometer above ground level, using Levitation Devices, Malacia was located over the ocean. Which ocean, or the location where it was sunk, is suspected to be somewhere off the coast of Tsuiraku, which is itself located in former Rinkai Erufu territory.
Spoiler: At the very end of the story, Meji Hinadori uses her new-found awesomeness to raise Malacia from its ocean grave and set it up as a "model city" -- modeling exactly what is an open question. There are hints that this doesn't end well, but that ending isn't part of Errant Story itself.