Rin Okumura, who was exposed as the son of Satan by Amaimon's attack, has been placed by the Order of the True Cross under the supervision of Shura Kirigakure. While he practices manipulating his blue flames, they learn of the theft of a dangerous item.
Rin is dispatched as part of the reinforcement unit to the Kyoto field office, which guards the hiding place of the Right Eye of the Impure King. The Myoda sect, led by Bon's father and responsible for the eye's defense, has endured the recent attack.
As Bon, Konekomaru and Shiemi try to deal with their responses to recent events, Yaozou summons the family heads of the Myoda sect. As they discuss the incident with the Right Eye, the group begins to question the mysterious actions of Head Priest Tatsuma.
Who is betraying the Myoda sect? Without high priest Tatsuma in attendance, the general meeting falls into chaos and ends without a conclusion. As Suguro resolves to find and question his father, he witnesses someone sneaking into the Kyoto field office.
Although the traitor was revealed, the Right Eye of the Impure King has been stolen. While confronting Ryuuji, Rin loses control of his blue flames in front of the gathered exorcists. In all of the commotion, Tatsuma slips Shura a letter addressed to Rin.
Shirou Fujimoto, Rin and Yukio's adopted father, encountered Tatsuma Suguro while trying to take the demonic sword, Kurikara. Tatsuma's letter reveals the circumstances of how the sword, which is the Myoda Sect's main object of worship, came to Rin.
The Impure King has been revived. In his letter, Tatsuma asks Rin to use the Kouma sword to fight, but will that even be possible? And to make matters worse, Mephisto suddenly appears with the news that Rin has been sentenced to death.
Miasma spreads through the streets as the exorcists begin to counter the Impure King's growth. Rin leaves with the other students to find Tatsuma. Yukio is on the front lines, unaware his brother has left his cell, when he notices something strange.
"You despise your brother, don't you?" Yukio is shaken as Todo tells him to admit his true feelings. Yukio reflects on the thoughts he's had since an early age. Meanwhile, Suguro has inherited the Gouha-en, and with it, he and Rin head to the sporangium.
The sporangium has finally burst, revealing the Impure King. Assaulted by the miasma, Suguro barely maintains the barrier. And every passing moment brings him closer to his limit. Rin questions why he can't draw his sword, even when backed into a corner.
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.
