Hayou no Tsurugi: Shikkoku no Mashou - S01

A girl named Rasutel-nicknamed Rasu-lives in the Floating Castle, where she fights demonic creatures. Chosen by the capricious Demon-Breaker sword, she embarks on a mission to rescue a princess taken by a Youki. Along the way, she’s aided by an unusual Youki named Anshu, who lacks the typical colors of his kind. But her journey is complicated by her younger brother, a demon-being who covets her golden eyes-a trait inherited from their father, the legendary Golden Youshu.