Now this is a good medieval fantasy manga.
I like these kind of stories on how war actually has an effect in the economy and it's benefits for the players in the war.
What the Queen said made sense socially and economically on why both sides want to keep the war ongoing. Heck, it actually happen in the USA during WW2.
Can't wait to read more adventures of the Demon Queen and the Hero.
PS: Here's the novels
official website and it's Japanese
wiki article.