TV Tropes says that the Naruto universe lives in Schizo Tech.
The universe essentially mixes feudal society with modern technology (and clothing). The only exceptions are things like cars and guns. The only fields of technology which are outdated are transportation and military.
It also goes on to explain that Schizo Tech is
The setting and timeline may seem at first to be The Middle Ages, The Colonial Period, or some Fantasy Counterpart Culture thereof, but when you look closer, you find polyester, robots, or other high-tech toys in between the horse-drawn wagons and wattle-and-daub buildings. There's generally no rhyme or reason for which technologies are anachronistically present besides the Rule of Cool.
So some technology exists while others do not.
- What does the term schizo mean? It's in schizophrenia and Schizo Tech
I think it's Latin or Greek but I don't know where else should I ask this.
After all, isn't schizophrenia an English word?