It is definitely possible to get all 4 ends on one save file. Once you see an End, it will be saved in the reminisce room and you will be able to continue from before starting the final battle. So you can simply do the following:I'm absolutely bummed that I can't get all 4 endings on one save file and had to hold off using my Buster end route save file which progressed further and got almost every CG barring the ones from the Casino. I went to finish Nightmare and Buster end route first and that may have been a mistake I think...
- Get Buster End, pick option to go back to before the battle.
- Go to town, remove Cheating Hearts at Fortune Teller in Slums until you have 2 or less
- Get Lust End, pick option to go back to before the battle.
- Go to town, lower Desire at Church until Falldown Mode is removed.
- Get Nightmare End, pick option to go back to before the battle.
- Get True End.