Mr. Yu's Code

Mr. Yu's Code is a note in Prey: Mooncrash.

Transcript
Mr. Yu asked for a place to secure valuables next time he visits. I have installed a safe in his office with a default combination [XXXX].

Please ask him to reset the code to something only he knows when he next arrives.

Location
It is hidden somewhere in Riley Yu's Quarters in the Crew Annex.