The 2 hours story of Volume 4 feel like an insult, after a hundred or so hours playing volumes 1-3, which are still as good as they were. I would be happier without this kind of bonus content....
Basically volume 4 disables EVERYTHING (if you think you kept something useful, you need to play 2 more story dungeons) you earned in previous volumes, your ability to choose were you go and forces you into a pretty generic linear story.... which by the way is told through what feels like 10 frames/second animations.
Minor spoilers in next paragraph
I mean, remasters are still good (no insane new features or anything), but when starting the last volume you get a notice that some (almost all) features are disabled, and after playing a little bit of story, Haseo gets a job extension, which disables use of all old weapons, and now you can only use the new weapon (for the record, every skill is an avatar skill on that weapon, so.... you'll be using that new avatar animation skip feature here). You play 6 dungeons or so in this shell of a game and that's it..... Game over....