If you are the kind of gamer who dubs himself a completionist, you will be willing to find each of the posters spread through the Metal Gear Solid V: The Phantom Pain locations. This guide is for you, then: we have found all the posters and this is where you can get them, too.
This is the most common kind of poster in the game. You will find one in the Eastern Communication Post, in the central building, on the side of a container.
Glamor Model Horizontal Poster is in the Eastern Communications Post, in the building you can find in the middle of the camp. It's in the same room where, during the C2W mission, you can find the equipment you have to destroy.
Another one is in Angola, at Nova Braga Airport, exactly at the biggest building in the north-western part of the airport.
You will find the vertical version of the Glamor Model poster in a small garage in the north-eastern part of Nova Braga Airport, Angola. It's on a wall between two shelves.
Idol Girl Vertical Poster will display some time at Mother Base, on the Command Platform.
You can find PF Soldier Posters only in Angola, even though they're quite common over there. A couple of them is at Nova Braga Airport, one at the terminal building, the other in the garages, both in the north-western part of the airport.
This Idol Girl Horizontal Poster will show up after a certain time, you will surely find it on the Command Platform after Mission 18.
