Sisters, almost certainly. Even if that wasn't the route that the story is obviously heading down, isekai manga as a genre is just too trope-heavy to let them be anything else.
Other Pillar: "So, Angie, Assassin, Anje, Anger-chan, Cheryl, or whatever your name is now, what was the wish you made for the resurrection god?"
Assassin: "Snow cone."
Other Pillar: "A... snow cone?"
Assassin: "Yep, cherry flavoured."
The Demon King may have gotten nearly a hundred levels suddenly, but he also got demoted from king to landlord. It's hilarious that his black magic skill is still only D-rank.
"As I finished my dance routine, I found myself wondering what every woman dancing around that pole wonders: will this make daddy love me?"
--Princess Clara, Drawn Together
I'm too squicked out over the thought of the king marrying his own daughter to be disappointed in the obviousness of the...
I rather like the intrigue. It's a nice change of pace from the very simple plots of most isekai manga. I agree that it's about time for a tonal change for a bit. We've had too many chapters with a high fight density.
Treating the elf girl as a flushable pet, as though we didn't already realise that he's a bad guy.
I'm amused by how the person who was arguably the weakest in that fight, Dahaku, was the one to get the XP for killing the Dwarf.
I will be rather disappointed if the Demon Lord isn't that Dwarf, or one of the royal family, but a character that hasn't yet been introduced. It would be amusing if the Demon Lord is that sword, though.