As explosions rock Alegium, church elders panic at Chirico’s impending approach. Several Erdspinnes rush into the temple’s courtyard and ignore the safety of pilgrims as they fight Chirico’s Burglary Dog. Chirico arrives and destroys several Erdspinnes in the courtyard before entering the main building. Godiba dresses up as a church man and sees mad Rochina talking to himself about Chirico, saying that Alegium will never bask in the light of glory again. Teitania rushes through an underground tunnel in her Order Buckler and thinks about what her father said to her. Montewells gets a battle report and declares that they’ll create a new age for Marteal once Chirico is defeated. Chirico tries to radio Godiba and runs inter several Erdspinnes that attempt to trap him with wires. He fires several mortars and in the confusion gets to higher ground to destroy the Erdspinnes. He then climbs onto an AT elevator, and at the same time Godiba reaches the medical room where Fyana is. He shoots at a technician who attempts to press an alarm button. Godiba rushes over to check on Fyana, and she asks when Chirico is coming. As Chirico rides the elevator, he comes under attack from Erdspinnes climbing the shaft on grappling wires. He destroys some Erdspinnes and shoots out the wires of others. He then fires rockets at the part of the ceiling they shot their wires into, causing it to collapse and destroy them. Chirico reaches the top of the shaft and is immediately attacked by Teitania, who punches his rocket launcher. Teitania identifies herself and claims that she’ll fulfill her duty to defend Alegium. Chirico comments that he must have bad luck to keep running into Teitania when he’s busy, and she tells him he has more trouble because Fyana is fully awake now. Chirico then opens fire and tries to run away. Montewells is informed that Gilgamesh and Balarant fleets are in orbit and have come to offer help in defending Alegium. Montewells calls both commanders and thanks them for their offers, but says their own defense forces can handle it and keep Alegium as neutral ground. Montewells orders Maori to activate Teitania’s auxiliary brain at full capacity, but Maori counters that they haven’t tested the control system or prepared Teitania. Montewells doesn’t care if only the auxiliary brain survives, because they can make another Nextant. A large gate closes in front of Chirico, forcing him to face Teitania. She tells him that he’ll have to defeat her if he wants to see Fyana again.
Maori activates the auxiliary brain, and Teitania suddenly rushes in to attack Chirico. She knocks away his machine gun and drives a harpoon into the Burglary Dog’s cockpit, injuring Chirico. Chirico responds by arm punching the Order Buckler’s cockpit, creating a hole. Chirico tries to punch her again, but she punches his cockpit multiple times and knocks the Burglary Dog over with a kick. Montewells watches the battle and mocks Chirico’s superhuman nature and status as the Untouchable One. Chirico stumbles out of the Burglary Dog’s cockpit and pulls out his gun. He falls over as he shoots the gun, and the bullet ricochets off the ground and goes into the Order Buckler’s cockpit, hitting Teitania in the auxiliary brain. Chirico wakes up and hears Godiba calling him over his helmet’s radio to come see Fyana quickly. Chirico asks about the refreezing, and Godiba tells him it’s too late. Chirico hears Fyana’s voice and rushes over. Teitania picks up Chirico’s helmet and tells Godiba that Chirico is on his way. She rips out her damaged auxiliary brain and says she can’t deny Chirico’s status as the Untouchable One. Godiba tells her that Fyana is dying and explains that the predicted lifespan of a PS is two years, which means that Fyana has used up her time. Godiba thinks that’s why Chirico and Fyana went into the cold capsule, so she can live eternally. But refreezing her won’t help now. Fyana cries out in pain and asks for strength so she can live for Chirico’s sake. She then remembers asking Chirico if they would wake up in a world without conflict just before they were frozen in the capsule. He thinks that they will, but no matter what they’ll be together. Just before freezing, Fyana asked Chirico to stop it because he shouldn’t have to go into eternal sleep because of her, but he said it was fine. A heavily wounded Chirico finally reaches the medical room and finds Fyana waiting for him. Fyana hugs Chirico and tells him they made a promise that they’d be together when they woke up. He apologizes, and she dies in his arms. Later, Rochina looks at the cold capsule, which is now Fyana’s coffin. He thinks she might’ve been the Untouchable One all along. Several months later, Godiba and Teitania drive through the desert, and he tells Teitania not to blame herself because Fyana was probably happy to see Chirico again. They stop when they see Chirico in the distance. Teitania gets out of the truck and calls out to Chirico, but he can’t hear her because a plane is landing nearby. Maori tells Chirico that the church wants to put the past conflicts aside, and Montewells wants to reconcile. Maori asks him to join the church, and Chirico angrily tells Maori to never approach him again. He says he has to be on his way and leaves. Recording the details of the incident, Rochina notes that Teitania never spoke to her father again. He wonders if someone can comprehend the real meaning of Chirico’s revival and what his destiny is. As Chirico walks through the desert, Teitania follows and declares that even if they never speak again, she’ll always love him because she understands he was the reason why she was born.
And so Brilliantly Shining Heresy ends almost as quickly as it began. Chirico has his final duel with Teitania, and she pushes him farther than any other opponent has. He only beats her because of the highly improbably luck of a ricocheting bullet hitting her auxiliary brain. Although Chirico finally finds Fyana, he only makes it there with enough time for her to die in his arms. Given how big of a role she played in the TV series, it seems kind of a waste to have her do almost nothing in this OVA but wake up and die. Fyana’s death is a sort of sad testament to Chirico’s fate of always being a lonely wanderer. Even after defeating Wiseman and the Secret Society, Chirico and Fyana weren’t able to enjoy their lives much before going into cold sleep. And instead of waking up in a world without war, they were revived into a world still at war to serve as the tools of a power hungry cardinal. We see here how little regard Montewells has for his own daughter, and he views her as little more than a tool for him to gain the papacy. He does get the title he wants, but at such a high cost so as not to be worth it. Our last glimpse of him shows a rather mad looking man helplessly clutching Teitania’s auxiliary brain. He sends lackeys to negotiate from a position of weakness, but that obviously doesn’t work. By itself, Brilliantly Shining Heresy is rather short, but now Chirico’s story afterward will continue through two other OVA series.