Mob Kousei no Ore Demo Boukensha ni Nareba Riajuu ni Naremasuka?

It has been decades since labyrinths first appeared in the modern world of Japan, bringing with them monsters and related catastrophes. With this brought many changes; the biggest one being a new profession called 'Adventurer' and the monster cards they use to summon their own monsters to fight and conquer labyrinths with.