Dragon Quest 9: Thief's Key Chest Locations
You can get the Thief's Key in the town of Dourbridge by speaking to Cap'n Max Meddlin, the Mini Medal turn in NPC for this game. All it takes is 4 Mini Medals to receive the Thief's Key, which is a bargain! As many fans of the Dragon Quest series know this key plays an important role to the game, allowing one to open many different treasure chests you couldn't otherwise.
There are some locations that I do not list on this page with chests that can be opened with the Thief's Key. The reason they're not listed is because they come later in the game after you've already acquired other keys, such as the Magic or Ultimate Key. Only one exception is the locked chest in Bloomingdale's mansion.
Magic Key Chest/Door Locations
Ultimate Key Chest/Door Locations
Stornway Castle Locked Chest
Enter Stornway Castle and take the northwestern stairs down to B1. In the locked chest you will find a Cautery Sword - there's another chest next to this one with a Mini Medal inside too, assuming you missed it the first time we came here. The pots and barrels next to the chests also contain some goodies too.
Chest Loot:
Cautery Sword
Porth Llaffan - Mayor's House
This one is really easy to find - you definitely tried opening it up when you came through this town. The Mayor's house is the northwestern most building in the town, use my map above if there is any confusion.
Chest Loot:
Pink Pearl
Slurry Quay - Behind Item Shop
Another extremely easy to find treasure chest - it's found right behind the Item Shop in Slurry Quay, next to another chest you probably got less than an hour ago.
Chest Loot:
Agility Ring