World Tarot use question?

Finally beat the game, that last boss sucked even with all the PotD gear.

But my question is:

I go back to Barnica Castle to save Catiua this time, do I have to go all the way back through the palace of dead to kill Nybeth and the final fight again to get the princess ending?

If I have to redo it all I guess I should do the Luira recruitment and the Floating islands before I save Catiua?