The Modern Dungeon Janitor

現代ダンジョン清掃員の俺、うっかり最下のラスボスをモップで絞め殺してしまう

In an awakened-Japan where dungeons have surfaced and licensed Explorers descend for fame and magic stones, the Janitors who keep the upper floors clean live in a different world entirely — looked down on, taken for granted, and definitely not supposed to be capable of much more than mopping. Which makes it a problem when one of them, just trying to do his job, accidentally strangles the lowest-floor final boss with the wrong end of a mop.