Meikyuu Gurashi No Boukensha Wa Dungeon Master Wo Yametai

Wade an adventurer specializing in labyrinths has come to a dungeon to obtain a detection artifact in order to seek revenge for his friends
He enters the dungeon with an exploration party commanded by a nobleman but a huge dragon blocks their way and they are wiped out
Wade fights the dragon with determination but he is defeated and fatally wounded However when he wakes up his wounds are completely healed and he has become a dungeon master
The labyrinth defense tale of the adventurer trapped in a dungeon begins