Adol Christin is cursed by a mysterious woman and becomes a Monstrum, a powerful being who can exorcise monsters. To escape from the city of Balduq, he must ally with five other Monstrums, each with their own unique Gifts, and stop the Grimwald Nox, a shadowy dimension on the verge of overflowing into the real world.

More details on the official game page of Ys IX: Monstrum Nox ...