“We'll kill all vampires. Sharing our own fallen "blood" as a weapon...!!” Arbitration Knights travel around the world to protect peace. Rinslet, a girl who has just become a regular knight, meets Yuri, a vampire girl with cool silver hair and crimson eyes. Rinslet learns that she is an abomination who kills her own kind by manipulating the power of blood armor, which materializes blood into swords, bows and arrows. She becomes Yuri's kin in exchange for her life, and her goal is...?