Boukensha Zettai Korosu Dungeon

Dungeons—marvelous labyrinths packed full of dreams where heroes gather in search of fame and fortune. Unfortunately, Eine and Nacht can't say they feel the same. While all the other reincarnated earthlings get to live out awesome isekai fantasies, the two of them are stuck slaving away as dungeon staff! And whether those inconsiderate adventurers win or lose, a messy pile of corpses will need tidying up. But if the two are disposing of bodies anyway...then what's a few more? Why not make their workplace a terrifying deathtrap from which none ever return? Maybe then they'd finally have some peace and quiet!

(Source: Yen Press)