I like the game, although I am a struggling a bit and do not feel like playing around anymore to find out the fourth ending, from now on it will be spoiler so be warned:
So, in order I first got the rosetta, then sakura, then 2 times the rosetta cursed. In the 2 rosetta cursed endings runs I got the same final day as both rosetta and sakura, only difference was than in both of these playthrough I opened the first locker, I could not find the answer to the second locker since the hint is the same and I did not see any different way of counting the princesses (funnily enough I first solved the enigma not by following the book but by looking at the appearence inside the game of the girls, I only noticed I did it "wrong" when I was trying to find another order for the numbers), except maybe counting how often the girls appear around but due to random events I do not think that is the answer, plus I am really not sure how to get to the second locket anymore lol. I also could only find the gem in the library, and not any of the other three, I paced back and forth a lot in the hallway to try for the white gem and to lower the music to zero (and later on also sound) for all the hall but nothing, I would have guessed that you could find the yellow gem in the sink when lowering the volume due to the whole "listening for the water key" but nothing, I also found nothing in the gym that is the only place where the "running" hint for the blue gem seemed to make sense. So yeah, any advice?