Ys IX: Monstrum Nox takes place in Balduq, northeast of Esteria in the Gllia region under Romun control. Balduq is known as 'the prison city' for its large prison facility inside the town and its architecture featuring high walls as a result of being built upon the fortified era. Furthermore the city is an important nexus for transportation in the region resulting in a wide range of inns, bars and trade centers. In more recent years public facilities such as theaters and baths are starting to be developed too.