You'll want to continue heading west, then up the top, and then into the next section to your left about midway. Upon reaching the top west side, you'll find yourself in a section that has acid water at the bottom and these jellyfish-type enemies called an Uoma and Ooma. When you're done, head back outside and go up north until you reach the top and then west into the path that will take you to a sub-area called the Overgrown Mound *** about midway, you can also find an opening to your left that will take you back to the Queen's Gardens. You can click here to learn more about this side quest.
The maximum amount you can deposit is 4500 Geo, however, if you deposit about 2500 Geo and more she'll leave her post with your deposited Geo. But in order to do that, you'll need to pay 100 Geo to open up an account. This path will take you to an NPC called Millibelle the Banker, speak to her and she will offer her services of depositing your Geo for safe-keeping. Upon arriving, head west where you'll find a sign pointing to your left. There are multiple ways to gain access into the Fog Canyon, but for this walkthrough, it is recommended that you enter the Fog Canyon from the lower side of the Fungal Wastes.
Fog Canyon Walkthrough Millibelle the Banker
