The quest "Unspeakable Secret" will also be updated. Let's finish exploring this area first, then turn in the quest later.
Now let's head back to near the house at the previous teleport point and walk onto the adjacent bridge.
After crossing the bridge, eliminate the enemies here and pick up the Dust on the tower.
After dropping down, climb the wall to the opposite side, eliminate the enemies ahead, and pick up the items along the way.
This item is the story item "Congzhi Leaf," which is required for Yu'er's quest.

