Intro. History In his heyday as a vampire hunter, Kaien was known as the "Fangless Vampire" due to his strength and skill, and for being born with an abnormally high amount of vampire genetic material compared to other vampire hunters, which he obtained by eating his twin. Thanks to his vampire DNA, Kaien was able to live more than 200 years, which is why he no longer appears to age. One winter night, Kaien naively agreed to hunt Juri Kuran, who was vulnerable due to the pregnancy of her daughter, Yuki. Juri spared his life and soon forgave him for his irrationality. At some point, they became friends, although Kaien still feels indebted to her. Kaien is also friends with the pureblood vampire, Isaya Shoto, and used to intentionally pick fights with him. After befriending Juri Kuran, Kaien took up Juri's dream of establishing a school for vampires and humans to coexist peacefully.