Time for the completely unnecessary "MC is the actual hero, but royalty/church pulled strings to make their puppet the 'Hero'" arc. Now the Assassin will have to face Karna alone, and none of the "Hero's party" will learn their lesson. I know it won't happen in this "pure-hearted idiot MC" manga, but it would be great if his boss showed up and captured the humans for eternal torment. Like an actual demon should/would.
P.S. The sudden appearance of inverted nipples was a surprise to be sure, but a welcome one nonetheless.