Pathologic 2

For those that would actually like to play the game, you will be able to get this achievement starting on Day 4 (7:30am-midnight). I believe your dead line is Day 7 to get it done. Starting on Day 4 while exploring you will sometimes hear a piano playing, you will need to locate which house it's coming from and then enter the house and speak to Capella at the piano. Afterwards you will have to do this same thing 3 more times to the random NPC's you find at the pianos. After locating and talking to the third person I believe the achievement pops after that even though there is another quest step to go and talk to Capella.
I personally would recommend making a save at the start of this day, and then just go all out looking for these people and then reload your save afterwards to get all your time spent on it back as sometimes they just don't like to spawn causing you to waste time looking for them. I think that they also will only spawn in normal districts, not infected or burned ones. Another thing to note as well is even if you find a person in one district, they can still spawn in that same one again as two of the piano players I got where in the same district upon re-entering later.

All the info I got is from QuentinCle95 and their great walkthrough here; https://psnprofiles.com/guide/10147-pathologic-2-trophy-guid...

All credit goes to them, would definitely recommend using it if you want a concise roadmap of achievement related activities that need to be done day to day.