This is the main Naruto theme, taking place in a loosely feudal Japan inspired world, with many heavily varied technological elements from numerous times in history, even the future. The main focus is within the Five Great Shinobi Countries, the Lands of Earth, Lightning, Water, Wind, and finally the Land of Fire in the center. The countries are ruled by monarch governments, often having shaky treaties active.
Hidden Villages within these countries are run by Kage, who all have equal rank to the individual leaders of the countries. Children are raised to be ninjas, going to Ninja Academies and learning both traditional school subjects in addition to ninja training. Ninja from most villages are usually for hire, doing work and supporting the village financially as well as themselves.
The series itself focuses Naruto Uzumaki, who dreams to one day be Hokage and create peace in the ninja world. Akatsuki as well as other dark forces threaten to destroy any chance of this peace and take control of it all, bringing the nations closer to sparking a full on war as they steal the nuke-like tailed-beasts, throwing off the balance of power between the countries with every successful capture.