Instructions
Create a new character, if you're not playing as part of the Resistance faction. During character creation, select to join the Resistance.
Proceed through the game, completing the Resistance quests. Once you've completed the quest "The Second Mission," you're ready to start "Catching the Water Thief Monster."
Travel to the Black Wing Territory, which is located within Edelstein. You'll find a hunched, grey-haired man named Surl here. Click on him to initiate the quest.
Walk to the far right edge of the map to enter the Concrete Road. Continue right to get to Concrete Road 2 and then 3. In the middle of Concrete Road 3 you'll find the Water Thief Monster.
Battle the Water Thief Monster. If you're a melee fighter, you shouldn't have any trouble. If you use magic, avoid casting fire spells, because the Water Thief Monster is resistant to fire damage. Instead, use lightning or poison. After you defeat it, the monster drops water bottles.
Collect the water bottles and then return to Surl. Next to him is a container. Drop each of the water bottles into the container, making sure to drop them one at a time.
Speak with Surl and he'll give you the Mechanical Chair, as well as 700 experience points.