Spiral: Series (2002)

Kill or be killed. That's how every day is for us. - The wheel of fate turned when Kiyotaka Narumi vanished. On that night, Kiyotaka's younger brother, Ayumu, was forever changed. Ayumu found himself thrust into the baffling mystery of the Blade Children. Who are they? What have they done to deserve their fate? Why do they believe Ayumu is the key to their salvation? Only one thing is certain: The Blade Children will stop at nothing to complete their destiny. And only Ayumu stands in their way.