Living in a rural village, twelve-year-old Touta Konoe yearns to reach the capital city with its towering structure that pierces the sky. His chance lies in defeating his teacher, Yukihime, who guards this dream destination. However, Touta's world shatters when a ruthless bounty hunter arrives, targeting Yukihime. To protect his mentor and companions, Touta undergoes a transformation by drinking Yukihime's blood, becoming an immortal being capable of thwarting the bounty hunter. Unveiled as Evangeline Athanasia Katherine McDowell, an ancient vampire, Yukihime flees with Touta to the capital, launching them into a thrilling escapade bound to alter their fates irrevocably.