The narrative centers on , a high school student and half-youmu who possesses immortality through high-speed regeneration. He meets Mirai Kuriyama , the sole survivor of a "Cursed Blood" clan of Spirit World Warriors, who initially attempts to kill him to fulfill her duty.
In the light novel’s most controversial move, Mirai does die. Her physical body collapses after she expels all her blood to pull Akihito back from the Void. There is no last-minute miracle. She dies in Akihito’s arms, and the novel describes her death with stark, painful clarity: "She was no longer a spirit world warrior. She was just a girl. And then, she was nothing at all." beyond the boundary light novel ending
: The novels focus more heavily on the internal mechanics of the Cursed Clan's blood and the specific lineage of the Nase family. The narrative centers on , a high school
