Maybe the first Vampire shigama doji fell in love with a Hiragi human longtime ago and wanted him to become a vampire so they could be together forever, and when the Hiragi refused, Doji got mad, and came to resent his immortality so he wanted to die too, but since that was hard to happen, he decided that the best chance in death would be to start a war between vampires and humans so to have revenge from both his dead lover and the vampires who live for so long. He cursed the whole Hiragi bloodline and destined them to start the demon army so they could fight the vampires. Then Mahiru came and started the Seraph od the end experiences, and Guren's friends died in battle and he brought them back, then the world ended.. and now here we are!!!
Maybe the first Vampire shigama doji fell in love with a Hiragi human longtime ago and wanted him to become a vampire so they could be together forever, and when the Hiragi refused, Doji got mad, and came to resent his immortality so he wanted to die too, but since that was hard to happen, he decided that the best chance in death would be to start a war between vampires and humans so to have revenge from both his dead lover and the vampires who live for so long. He cursed the whole Hiragi bloodline and destined them to start the demon army so they could fight the vampires. Then Mahiru came and started the Seraph od the end experiences, and Guren's friends died in battle and he brought them back, then the world ended.. and now here we are!!!
That sound just about right