Treasure Chest Key

Treasure Chest Keys are dropped by monsters, and they can open certain treasure chests.

There are many places that require the use of Treasure Chest Keys, however, they are not cross compatible:

• Treasure Reward rooms in Dungeons (the keys are always gained from one of the monsters that spawn in an Orb Room)
• Solea Mountain caves
• Connous Underground
• Courcle and Rano Exploration chests

In the case of the exploration chests, only the key dropped by the monsters that spawn with the chest open the chest. You can't use a key from a previous monster spawn to open a new chest. Also note that even if you have the key for the corresponding chest, you cannot open it until all the monsters have been defeated.