In Orario, the only place in the world that hosts the entrance to the massive subterranean Dungeon, there's a certain tavern where the most desperate and vulnerable bring their troubles. There, the ex-adventurer Lyu Lion uses her terrifying strength to wrest what justice she can from the shadows of the Labyrinth City! But when a girl goes missing and all evidence points toward the powerful Grand Casino, she may need more than brute force to help...!