Drushka's suspicions were correct. Rebirth logs show that a man named Athetos came here once before - hundreds or possibly thousands of years ago.
About the Note: 
Edit
This is a purple note, and written in English by (an) Athetos.
The note mentions a mysterious character named Drushka, who does not appear in-game.
This is Note 21.
Location Edit
Mar-Uru on the upper left side of the shaft below Athetos.
