Rise of Edwin Von William Highland

Edwin Von William Highland is a prince and the only heir to the Kingdom of Highland. As a reincarnated person from Japan, he aims to use his knowledge to help his poor Kingdom get stronger. His loving father has already taken steps to aide his son to become a great King but everything changes when the Demon King arrives.
How will Edwin Von William Highland deal with betrayal, loss of loved ones, political opponents, and the demon kings army that marches across the land?