Hai to Gensou no Grimgar volume 20 read:

It's been a long time since the previous Grimgar book.  The previous enemy of the series, orcs and goblins and undead, had been supplanted by a giant black ooze, which was the new world menace.  The remaining living heroes of the story were Ranta, Yume, Haruhiro and Shihoru, who happen to also be my favorite characters in the series.  Shihoru was off in some tower doing something, but the other three were together and worked to defeat this new menace.

Ranta and Yume had enough time to get together and have a child.  Humans made an alliance with the undead to defeat the black ooze, and they succeeded.  The problem is the black ooze had been paralyzing the gods Lumiaris and Skullhell, who were now unleashed back into the world.  Because Ranta was a dread knight, a servant of Skullhell, who desires wanton death and destruction, Haruhiro had to put him down before he hurt others.  One more main character down.  This series really isn't forgiving.

Then there's a big time skip and the story focuses on new main characters, the descendants of Yume and Ranta.  Two dragon tamer princesses, of all things.  They plan on visiting Grimgar to see what all has changed during the big time skip.  The plot is a bit loopy, but that's always been the case with Grimgar.  The story never knows how to sit still and focus on one thing.

I assume it will be a long time before I get to read the next volume of Grimgar as well.  The story is already random enough, the long gaps between when I can read it doesn't help.  But the strength of this story is more in the narrative style, the stream-of-consciousness that somehow grasps how people think in stunted, unformed manners, rather than clear and sensible logic.  People don't actually spell out in their heads everything they're going to do and why, they think in a much more rapid and instinctual way.  The brain is often left trying to rationalize what already happened.  There's plenty of Haruhiro stream-of-consciousness in this book as well, so I thought it was a nice addition to the overall work.