Backstabbed in a Backwater Dungeon Vol. 3 (manga)

UNLIMITED GACHA VS INFINITE EVIL!

Light and company find their adventuring interrupted by reports of suspicious killings in the very same dungeon they're crawling. Tempted by the prospect of boosting his rank-not to mention the generous reward promised by the Dagas Adventurers' Guild-Light sets off to catch the killers. The hunt takes a personal turn, however, when a party of innocent young adventurers gets slaughtered in the crossfire.

Light's quest for vengeance will have to wait as he turns his wrath on a new target!