This Seeking Tech guide will show you how to start the side quest called A Promise of Treasure in Ghost of Yotei.
To do so, follow the video and text guides below:
The quest giver you need to talk to won’t appear until you meet some very specific criteria.
You first need to complete the Echoes of the Strom quest at Benten Port.
Afterwards, fast travel to the entrance of the port. You need to look for an enemy attack, either right in front of you or a little bit to the left of the entrance.
If you don’t see any skirmishes, fast travel somewhere else and then fast travel back to the Benten Port entrance until you see a fight.
Once you see an enemy attack, kill the enemies if you want and then manually go to the house near the Onryo Gift Altar.
If you see someone running into the house, then you should be able to talk to someone inside to start A Promise of Treasure.