Hello Euphoria,
That picture is currently not accessible in the demo, but will be in the full game. Think of it as something to look forward to. I want to give people a fun and memorable experience inside and outside of the game. I promise it will be worth it once opened, but for now it is an unanswerable easter egg.
I am glad you wanted to see what it was though, thank you so much for playing the demo, and I am glad you are invested!