When a series is cancelled quickly, mangaka have two options: rush through to the original ending and try to make a point out of all of it, or just end it and assume that the fans can fill in the blanks. This series chooses the latter- it lays out what would have been one big final arc and then leaves it up to the reader to finish. Which means it's not at all satisfying! There's no big unifying theme or anything, it just ends and hope you care enough about the characters (it barely had time to flesh out) and the world (it barely had time to explore) to find your own ending.
And so Hell Warden Higuma sputters toward an end, which is a shame because the first volume held so much promise. I can only think that a quick cancellation forced the unfocused, unsatisfying ending. Hokami's afterword says they would like to continue creating Higuma manga, so I hope that comes to pass. I would be open to reading their other works.