The Kataart Mountains (Japanese: カタート山脈さんみゃく Romaji: katāto sanmyaku) are a mountain range at the northmost point of the peninsula within the mazoku barrier.

Prior to the Kōma War, the Kataart Mountains were known as a holy site, home to Aqualord Ragradia and countless ryūzoku. However, after the war, the mountains became primarily known as the location where a fragment of Ruby Eye Shabranigdu lies frozen in ice as the Demon King of the North.

The Mountains are rumored to now contain many lesser demons. This is of great concern to the Kingdom of Dils, which shares its northern border with the Mountains. King Dils II once led an army into the Mountains to slay the demons and destroy the Demon Lord of the North; all of the soldiers were lost, and Dils II was cursed with the Raugnut Rushavna.

A small part of the mountain range, called Dragon's Peak, remains the territory of the ryūzoku, who guard the original Claire Bible, which is hidden in an extradimensional space nearby.