Book 1

Abandoned as a baby and raised in an orphanage, the kind-hearted high-schooler Yuki Sakuragi is driven by a need to find the reason for his existence. Plagued by mysterious dreams, Yuki also possesses the strange ability to read the deepest, darkest thoughts of anyone he touches. As both the dreams and his powers intensify, there appears before him a beautiful young man named 'Zess,' whose face tugs on Yuki's memory. He warns Yuki not to venture outside on Walpurgis Night, the eve of the blood-red moon, which invites death. But when Yuki's compassion leads him to disobey Zess's order, has Yuki carelessly thrown his life away before he's even given himself the chance to find out the very reason for it?

Book 2

Welcomed into the arms of the Giou clan and the Zweilt, Yuki reaches out to his comrades even as he is drawn into their war with the darkness. But the demonic Duras continue to spread their malevolence around Yuki, and the members of his new family are not impervious either, as one of their own vanishes without a trace and yet another is cornered by a sudden ambush. In the Zweilt, Yuki may well have found the long-sought-after place he belongs, but the enemy seems intent on stealing it out of his grasp forever. And when the shadowy figure of 'Reiga,' the nemesis of the Giou, finally steps into the light, will Yuki find himself utterly alone, crushed by the weight of the truth?

Despite finally learning more about the 'Sunset of the Underworld' a thousand years past, Yuki finds his thoughts returning once more to his former friend and current enemy Kanata . . . But while Yuki may be new to picking sides in a centuries-old war, it is nothing new to the Zweilt. And Kuroto and Senshirou, the new Zweilt pair Yuki has only just encountered, harbor a profound hatred for Opasts, swearing revenge on one in particular. What happened four years ago to inspire such loathing? As Yuki bears witness to the flames of revenge that burn in the hearts of those around him, how will his own heart respond to the betrayal that he cannot forget?

In their war with the Duras, the Zweilt rely almost entirely on the power of the bonds between them and their allies. But with each battle and every passing reincarnation, is there not the danger of cracks developing in the glue that holds these warriors together? When a tense, unexpected battle with an Opast general is cut short, one pair is forced to reconsider their disparate oaths of vengeance and what seeking revenge truly means. And before another battle can get underway, the final Zweilt pair joins the fray at Twilight Hall. But while Yuki seemingly becomes fast friends with one half of this new team, the heart of the other seems vaguely unreachable, clouded by memories of the past...