Roselia Oukoku Monogatari: Kikoushi to Akai Kami no Otome

The Kingdom of Roselia, the "Land of Roses," has just crowned its young 17-year-old queen, Roselia. At the ceremony, which attracts many guests from other countries, she is promoted as "a talented young woman and an exquisite beauty" in order not to show the weakness of the country. But powerful countries target the small frontier kingdom and infiltrate it with assassins who want to kill the queen! In the meantime, the gentile Hernan has become Roselia's confidant, but his identity remains mysterious... (Source: Akita Shoten, translated)