I have a detailed walkthrough here if you want to know more about the game in general, it's the third download option. But since you wanted hints, here they are:
HINT NUMBER 1 is that the lewd scenes in the gallery are ordered by their order of appearance in the story (you can view all of them on a single screen, if you didn't know that). That should give you a rough idea of where you can find it.
HINT NUMBER 2 is that you should be as reckless as you can.