Honestly, it felt like either the author was tired of thinking up genuine plotlines, or just wanted to end it on '100'. Or it was axed/rushed, but I don't think so.
________________ There are times when you will miss what you never had. I wonder how you will find what you so desperately need.
Yeah, it does end in a way that opens the door for a sequel, but I'd rather not read the sequel it sets up--which appears to be a repeat of the story arc we just had, except set in heaven instead of hell. (I'm aware the authors probably did this on purpose to give the manga a "life continues on" ending instead of literally setting up a sequel.)
Theoretically, a reboot of this series could work out great. The manga had a lot of good ideas in it, but most of them weren't executed all that well. (In the reboot, I vote for canning Idamaria, making Samus lead female, and not screwing over Elimona's character. A little more setup for turning Shugarl into a good guy would also help.)