RPG Insanity

Hi, was wondering if it was possible to save the game after you beat Dakren. If I want to grind out the game and beat the danger areas and the heroes cave and the goddess shrine, do I just have to leave the quest unfinished?

Yes you can. The game will send you back to before the true ending boss fight where you can leave the dungeon and tie up any loose ends.

When I check the quests, it says that I still need to kill him, so is the quest just going to remain unfinished?

Yep. That's why you don't get any EXP and so you can challenge the true final boss as many times as needed.