Where is the Witch House in NTE? How to unlock it?

The Witch House is a hidden exploration location in NTE, located in a concealed valley on the outskirts of the Hethereau region. Unlock requirements: 1) Complete Main Story Chapter 3; 2) Find and read the "Ancient Diary" item while exploring Hethereau; 3) Go to the marked location and talk to the NPC to trigger. The Witch House contains: multiple chests, a hidden boss fight, unique furniture blueprints, and an important lore storyline. Bring combat-ready characters as the hidden boss inside is quite challenging.