After his secret is exposed, Rin takes part in a special mission along Shura and Yukio to retrieve the "Left Eye of the Impure King", a demon relic that was stolen from the True Cross Academy's vault. In the occasion, they fail to retrieve it, but discover that the culprit is Saburota Todo, one of the exorcists in charge of the vault that was corrupted upon being possessed by a demon. After hearing that there was an attempt to steal the Left Eye's sister relic, the "Right Eye of the Impure King" in Kyoto, the Order sends a team there to investigate, including Shura, Yukio and the Exwires, who are in conflict after learning the truth about Rin.

The Exwires arrive at Kyoto, and Ryuji, Konekomaru and Renzo take the opportunity to reunite with their families, while Rin and the others tend to the Exorcists of the Myoda Sect, who got wounded guarding the Right Eye of the Impure King. In the occasion, Rin meets Ryuji's father, and learns that Ryuji is resentful of him, as despite being the leader of the Myoda Sect, he is not respected by the others, as he relegated his duties since the Sect, which was weakened after losing several of its members on the Blue Night, joined the True Cross Order. Meanwhile, Todo, with the Left Eye of the Impure King replacing his own, contacts his mole inside the Sect, planning another attempt to steal the Right Eye.

Rin finally manages to draw the demon sword. Shura tells him to, “Win a place for yourself in this world!” However, there doesn’t seem to be a way to stop the Impure King’s overwhelming growth. And if Suguro’s strength fails, the barrier will collapse!

The sight of a blue flame burning in the night sky is reminiscent of “Blue Night,” but has brought about a completely different result. Now that the incidents relating to the Impure King have been concluded, those affected are moving on.

Based on the title chapter from the Ao no Exorcist: Spy Game short story collection novel.