Just playing around with an idea.

You will have to go to the camera shop to get film before taking any pictures. Walk out of either end of the train car to enter the city. The camera shop is to the Southwest.

Press Ctrl in-game to take picture. You won't be able to look at the picture, but it will affect things in-game. I suggest talking to every NPC before taking any pictures.

Press Shift in-game to view how many frames you have left, as well as how many subjects were detected in the last photo you took.

The background tiles are all created by me, but the sprites are blatantly stolen from the example game.