The Sukhothai area in has different Mystery side quests you can solve, including which rewards you with Adventure Points for completing it.
The puzzle in this Mystery is tricky, demanding you find a hidden combination to a locked crate. You have to use clues found by exploring important areas if you want a chance at solving this Mystery.
Unlike Mystery in , is a quest that can be completed in Sukhothai alone. You don't need to retrace your steps in any other region to find the answers to this Mystery.
This makes a great side quest to pursue once you enter the area since the rewards from solving it can help make you stronger for the main story.
To start you must travel to Wat Chana Songkhram, an area in the central north of the larger Sukhothai region.