The Reverie Corridor is an extradimensional space created by an ancient race known as the gnomes.
Trails of Cold Steel
The Reverie Corridor is not present in its current form during the events of Trails of Cold Steel, instead being the Realm of the Great Shadow.
Trails of Cold Steel II
The schoolhouse returns again to challenge Class VII's skills, and how far they've come since their last skirmish. The school bell rings and an azure glow once again appears around the facility much like the events during Trails of Cold Steel. The only difference is that the barrier is missing. Once Class VII enters, they see what looks like walkways suspended in a void unlike the Realm of the Great Shadow. They make their way through the four levels of this extradimensional realm, at the end encountering a portal made of "white shadow". They enter it and find themselves in an area similar to the one found at the end of the Realm of the Great Shadow, where they encounter Loa Luciferia
The design of each floor (four in total), as compared to the Old Schoolhouse, changes every time you leave and re enter the schoolhouse. Monsters you've slain or treasures you've procured will respawn.
Perks of the Dungeon
Gamers who challenge the dungeon can purchase Phantasmal Mirrors at the base of the dungoen. In that your characters can equip different mirrors. These mirrors in turn transform the said Class VII member into fighters that Class VII has met during their adventures. Each of the 5 mirrors cost 200k each.They will also receive the new character's Quartz set, replacing the original Class VII fighter. However, these forms can only be used in this dungeon.