"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...? A Yuri x Vampire x Dark Fantasy!