Milieu island

I discovered what the underlying cause is. It is as I predicted, but it's difficult for me to argue and take care of by myself. No one will believe it by through my own story of what I've seen, so I need proof. I also need someone who can make a precise argument with that proof. First, the proof. Find the Marks of a Thief from the old tree in the Milieu Island. It seems that the Marks of a Thief is using the Ghost Thieves to attack the merchants. Maybe if you remove the Marks from that place, they'll stop attacking the merchants. I have not tested this, so I don't know. Regardless, when you find the Marks, go to Elder Sharin Hyren in Tor Fortress. I am referring to my sister. My sister will be able to make the fairest and the most righteous judgment of anyone. If my sister passed judgment on this, no one will be able to oppose it. I shall entrust you with this task. May there be spirit's revenge turn on those who turn their backs on you.

Recover the Marks of a Thief from the old tree in the Milieu Island and go to Elder Sharin Hyren in Tor Fortress. May there be spirit's revenge turn on those who turn their backs on you.

Welcome traveler. Is this…the Marks of a Thief? Sara sent you, I understand. Can you wait for a moment?