Mitsugare Hime to Reigen no Byakurou Ou: Juujin no Mannouyaku ni Naru no wa Iya na node Zenryoku de Toubou Shimasu

One day, Nina, a young girl living in the forest with her foster father, "Master," is suddenly attacked and kidnapped by an emissary from the neighboring country of Uruzgand. Confused, Nina opens the letter her Master entrusted to her. In it, she finds that Nina is "the princess of the Holy Kingdom...

Source: MyAnimeList