Rennyu Order The Animation

Taiyou no Hime
One day, the hero, Takayuki, who lives alone in Japan, away from his parents in a distant country on an archaeological dig, is suddenly visited by the brown heroine Sasha, the princess of the mysterious country of Al Fajar. She is carrying a letter from his father, which says that Sasha has become Takayuki's wife. Takayuki is puzzled, but Sasha immediately asks him to marry her so that she can give him an heir.

(Source: Getchu, translated)