Tenjou Renka: Kin no Oujo to Hi no Kusushi

Northern Song Dynasty, during the reign of King Huizong: Aila, the princess of the Golden Kingdom, is assigned to visit the capital of the Song Dynasty as a goodwill ambassador on behalf of the royal family. However, on her way, she is attacked by assassins. She falls in love at first sight with Rinshi, a young fireworks maker from the Song Dynasty who rescues her. But there is talk of a marriage proposal with the ninth prince of the Song Dynasty, King Kang...?

(Source: Akita Shoten, translated)