Rasu, a resident of the Floating Castle that combats demon creatures, receives a commission from the resolute Demon-Breaker sword-bearing lady to rescue a princess abducted by a Youki. Alongside the enigmatic Youki named Anshu, who possesses an atypical hue for his kind, Rasu embarks on her mission. Meanwhile, her younger brother, driven by his fixation on their father's Golden Youshu lineage, obstructs her progress with his demon-oriented mentality and desire for her golden eyes.