The Kingdom of Dils (Japanese: ディルス王国 Romaji: dirusu ōkoku) is a country located in the northern area of the mazoku barrier. It is bordered by the Kataart Mountains to the north, Kalmaart to the east, Ralteague to the south, and Lyzeille to the west.

Significant locations in Dils include Gyria City and Dragon's Peak.

The king Dils II (Dils Rwon Gairia) ruled the country until he was cursed with the Raugnut Rushavna after an ill-fated expedition into the Kataart Mountains to challenge the piece of Ruby Eye Shabranigdu imprisoned there. The kingdom was later ruled by Dynast Grausherra under the guise of King Wells Xeno Gairia, until Lina Inverse and her companions exposed and defeated him.

Lina got the idea for the Giga Slave spell while traveling to Dils with her sister, when she heard an oral recitation of material from a Claire Bible manuscript that was later destroyed by Xelloss.

The events of the novels Gaav's Challenge, King of the City of Ghosts, The Strategem of the Army of Dynast, and Road to the Demon's Reincarnation take place wholly or partly in Dils.