I doubt it's a random chance to get 97. I got the wallpaper on one game by talking to the specific TV guy, and then I loaded my other game and did the same thing. I got it right after talking to the correct NPC. Maybe you missed something? Sometimes I have to interact with those blue blobs in the marigoddess world like three or five times before I even get the wallpaper just for them. And you need to use the lantern on them, in case you didn't do that.