You will get this for completing the flashback sequence which will be started as soon as you talk to the folks in the diner. This one is unmissable
If you get stuck at any point in the flashback, refer to the video below! (The flashback starts around minute 35.
(video credit: The Killer Bits)
Hope this helps you guys!
Any improvements? Please let me know in the comments below!
P.S. be aware of the missable achievement in this flashback!