Next, head to the village entrance and speak with this captain again. Hand over the letter we obtained earlier to complete the "Unspeakable Secret" quest (no reward). After completing this quest, the collection rate for the first map is 92% (Dragon Pillar defeated, but not the third phase). If you've missed anything, check the title for a checklist.
We need to continue advancing the main storyline to access the area on the left; we can return here later.
