XP Shell

The XP Shell (XPシェル) is a mysterious structure floating above Archia City, which can be accesed from the topmost floor of the Tower of Origin. The name is a contraction of eXecute Progress Shell, and also serves as a dungeon in Ar tonelico Qoga: Knell of Ar Ciel. Depending on the actions taken by the player, this could end up being the final dungeon in the game.

History
(more coming later on...)

Layout
The XP Shell itself is separated in two parts, the second of which is closed off by a barrier wall during most of the game. The first part is accessed from the Tower of Origin, and contains a relatively small maze filled with treasure chests, and the entrance to the Module Harvestasha where Harvestasha XP is located.

The Shell also doubles as the final dungeon for the True Ending route in Ar tonelico Qoga: Knell of Ar Ciel, and also marks the point of no return in the game: after the Shell has been shot into the Planetary Core, it's impossible to go anywhere else, reason why the game advises saving in a separate slot after this event. The area opened after said shooting is also home to the final treasure chest in the game. Given this, the player will know if he/she collected all the treasure chests present in the game depending on if the trophy notification pops up after opening it. This area also requires operating a switch to open the gate leading to Module Harvestasha, and has a couple of event battles: one immediately after arriving at the Planetary Core, and other right before operating the switch.

As for monsters, this area is the place with the strongest monsters in the game, which also makes it the perfect place for gaining levels if you plan to obtain the trophy awarded for getting every party member to level 99. It's also home to the strongest Antibody-class monsters, which have as their rare drop the Ar tornado: a bomb-type item that can't be found anywhere else, and it's also the only form of attack capable of damaging Ar Ru during the second battle with her.

Normal Area

 * ?Shiny Clothes?
 * ?Mythic Armor?
 * ?Maiden Tears?
 * ?Ultimate Drill?
 * ?Vintage Board?

Area Accessible After Entering the Planetary Core
Number of Treasure Chests in this Area: 6
 * Angel Recoverael

Enemies
Number of Random Encounters in this Area: 10
 * Type 2 - Annihilation
 * S-01
 * Furia Model I
 * Furia Model I-B
 * Furia Model III
 * Furia Model III-R
 * Doll Model HBL
 * Doll Model HBL-S
 * Doll Carrier Type H

Encounter Probability: Middle

Bosses

 * Richa
 * Doll Carrier
 * Zzx_Ru & Eggs
 * Ciela