Whee. Nice to see this series continuing.  I always like new world order or alternate world order sort of stories.  While the original series didn't "need" a sequel it's still nice to have one.  As for Melody and Ashley, my guess is that the humans up north have come up with a way to hunt or trap giantesses.  Looks the old world order of "giantesses hunting humans and rich humans thinking themselves untouchable behind city walls" came crumbling down during the climax of the previous story.  Yep.  Rich people don't care if poor people get eaten, but threaten the rich people and suddenly the hunters become the hunted.

Poor Dagon, everyone wants him but there's only one to go around.  At least he has a bunch of women who care about him.