Sword vs gun, wyvern vs fighter jet, what happened when your typical magical world meets the modern era technology?

Follow Eric the unfortunate soul who has been reincarnated in another world... as a girl(?) and as princess nonetheless. Follow him (or her in this case) as she create a modern country in a world where magic rules and society stuck in Roman era.

Note : English is not my first language so expect some grammatical errors and others mistake