So, I've realized why nothing worked. The issue was that I turned Always Dash option ON. Don't turn it ON because none of the save files will load.
And generally the game is good, a good classic JRPG. I tried both ending where you join Neptune's son and where you reject his offer. Honestly I like the option where you join him more, I really like that idea of "We'll destroy the world in the name of our love". Music is good and immersive, but nothing super special.
Now I'm in peace when I have finally finished the game. Wish you made some sort of sequel, but I doubt that you will ever return to RPGmaker games ever again.
So yes, 10/10!