Tasogare no Kishi Akatsuki no Sora

Six months after King Hyonjong ascended to the throne, the Dai Kingdom was on its way to revival. However, the king, who had gone to suppress a rebellion, did not return, and Taiki disappeared without a trace. The female general Yi Sai, worried about the loss of the king and the kirin, goes to Gyeongguk, risking her life to ask for help.
(Source: Shinchosha, translated)