Unable to remember the past, high school senior Saya Otonashi must rediscover her destiny in order to defeat the chiropteran vampires that threaten her loved ones' existence.

قام ساموراي لورد بإعطاء أعضاء ابنه الرضيع إلى ثمانية وأربعين شيطانًا مقابل الهيمنة على ساحة المعركة ومع ذلك، فإن هذا الطفل الذي قد تم التخلي عنه يبقى على قيد الحياة بفضل طبيب يزوده بأطراف إصطناعية وهي الأدوات القاتلة التي سيستخدمها الابن المظلوم لمطاردة الشياطين لاستعادة جسمه قطعة واحدة في رحلته يواجه يتيم يدعي أنه أعظم لص في اليابان

تجري أحداث القصة عام 1924 في بلد صغير يدعى "ساوفيل". بطل القصة "كازويا كوجو"، الابن الثالث لضابط من الحرس الامبراطوري تم نقله للدراسة في اكاديمية "سانت مارغريت"، حيث الأساطير الخرافية وقصص الرعب هي الصيحة الحديثة. هناك يلتقي "بفكتوريكا" فتاة غامضة لكن جميلة وذكية، لا تحضر الحصص بل تقضي أيامها بقراءة كل محتويات المكتبة أو حلّ الألغاز.

The anime's setting is a fictional Japanese city named Sugomori City. One day, Noriko Sonosaki tells her classmate Katsuhira Agata, "You have been selected to be a Kiznaiver." The Kizuna System, which allows Katsuhira to share his wounds, connects him to the classmates whose lives and personalities completely differ from his. The Kizuna System is an incomplete system for the implementation of world peace that connects people through wounds. All those who are connected to this system are called Kiznaivers. When one Kiznaiver is wounded, the system divides and transmits the wound among the other Kiznaivers. Sugomori City is built on reclaimed land, but as the years go by, the city's population is decreasing. The story is set in this town where Katsuhira and the others live.

The legendary swordsmith Kiki Shikizaki created 1,000 swords in his career. The more of the swords a country owns, the higher its chances are at winning a war. When the shogun emerged victorious, he collected 988 swords, but these were merely the “practice pieces”. The last twelve swords were the crowning achievements of Kiki’s career. Each one of them is so powerful that a single man could defeat an army with it.

Togame, the shogun’s strategist, gets the order to collect these swords. At first she hired a ninja, but each of the swords’ value is so high that the entire ninja clan went rogue once they got hold of one. She then put her trust in another warrior, but he kept the sword for himself. Her final hope now is Shichika, the seventh and last student of the Kyotoryuu School.