Murdered by a demonic being, 15-year-old Yuji Sakai has his life force replaced by a flame that dims with each day. When the flame dies, no one will remember he was ever alive. This is how he meets Shana: a warrior with a burning sword, and the will of a god as her guide. The two form a bond as Yuji becomes Shana’s accomplice in her battles to keep the balance between the ordinary world and hers.

Shana and Alastor — the Lord of the Crimson Realm — continue to do battle with the Guze no Tomogaras, who are trying to steal the Power of Existence from mortals. In the last battle, Yūji is revealed to be a mystes, a torch with nearly unlimited Power of Existence. Since the Tomogaras want to capture Yūji and use him to upset the balance of the Realm, Shana resolves to protect Yūji. Yūji then vows to join Shana in her fight.

Both Shana and Kazumi stand at their respective locations waiting for Yuji to meet with one of them, only to discover that Yuji has disappeared, with not even the slightest evidence of his existence left behind. All is not lost however, as the letters the two of them sent to him still give hope of Yuji's continued existence. As Shana and company search for answers on Yuji's whereabouts, they soon find the truth staring back at them when Yuji reappears in front of them as the leader of Bal Masqué. Left with little choice, Shana must now confront her most unlikely adversary on the battlefield in her toughest challenge yet.