Hoshifuru Oukoku no Nina S01

Nina, a girl who lives as an orphan in the fortress city of Fortuna, has deep blue eyes, like lapis lazuli, a color similar to that of the god of the stars. Also, this color is exactly the same as the eyes of the recently deceased princess, Alisha. For this reason, when the second prince of Fortuna, Azur, finds Nina, he orders her to live as Alisha instead. As the substitute princess and the priestess of the stars, Nina is tasked with being chosen as the fake bride of the first prince of the neighboring land, Set, from the great country of Galgada, after three months.