迷宮クソたわけ 最弱魔法使いは借金返済のためコツコツ冒険をくりかえす (Associated Names)

The boy captured in a s*ave hunt is bought by a merchant and forced into the path of an adventurer. The boy, whose aptitude for adventuring was catastrophically low, reluctantly ventures into the labyrinth as a wizard – a role anyone can take on (and the one who is the most likely to die).