Hazure Yuusha Datta Ore ga, Sekai Saikyou no Dungeon wo Tsukutte Shimattan da ga?

High school student Maruo Anai is suddenly summoned to another world with his classmates. While his classmates are given powerful Jobs as Heroes, Maruo is granted the seemingly useless Job of [Hole Digger] and is branded as a "failed hero."

Accepting that he couldn't expect a hero's success, Maruo was just digging a hole by himself when he accidentally touched a Dungeon Core he found, turning him into a [Dungeon Master]!?

Having gained the power of both the [Hole Digger] and [Dungeon Master], Maruo intended to create numerous cute monsters (fluffballs) and enjoy a comfortable dungeon life. However, his constructed dungeon is somehow deemed a threat...

The world starts to view his dungeon as a major catastrophe-level threat, as he's unconsciously mass-producing monsters stronger than the Heroes!