Aramis warns Misha about Raphael's impending threat to destroy the Machine Empire, but her warnings are dismissed, and command of her troops is transferred to Juggler. Meanwhile, Karen discovers that a ball of light has landed near her and Teppei's hideout on Kamui Island, and her B't Shadow ventures out on its own. As Teppei, Fou, and Hokuto approach The Area, they arrive at the ruins of Fou's hometown, Sodom. There, they encounter Quatro, one of the Seven Evil Knights and a former friend of Fou's. Fou decides to stay behind, and Teppei learns that their enmity arose from Fou allegedly killing Quatro's little sister. Teppei faces an attack from Ryukan soldiers under Juggler's control and realizes they are being used as sacrifices. He frees them from Juggler's influence and learns that Fou has surrendered to Quatro. Determined to save Fou, Teppei heads back to Sodom.

In a flashback to Fou's troubled childhood in the war-torn Sodom, he rejects the teachings of the church where Lily and Quattro tried to befriend him. During a raid, the church is bombed, leaving Lily on the brink of death. Quattro asks Fou to give her hope, but Fou's skepticism prevails, and Lily dies. In the present, Quattro relentlessly attacks Fou, who won't fight back due to guilt. Teppei steps in but realizes Quattro's immense strength. Quattro seriously injures Je t'aime and engulfs Fou and Je t'aime in a fiery attack.

In a flashback, Lily is buried on a hill on the outskirts of Sodom. As Quattro vents his anger on Fou, Machine Empire soldiers bomb what's left of the city, taking the unconscious boys to become future soldiers. In the present, Fou survives Quattro's attack thanks to Je t'aime's sacrifice. Teppei condemns Quattro's vengeance, claiming he's blaming Fou for his sister's death. Quattro easily incapacitates Teppei but Fou decides to win to uncover the Machine Emperor's intentions. When Fou plays a funeral hymn on his violin after seeing Je t'aime's ashes, he unexpectedly starts playing the song of the angels, resurrecting Je t'aime as a "true phoenix." They defeat Quattro with a powerful attack called Fortune Symphonic, connecting with him psychologically. Quattro, on the verge of death, asks Fou to kill him, but Fou refuses, burying him beside Lily.

As Teppei and X journey towards The Area, they're pursued by the repaired and enhanced Metal Face and Madonna. They stumble into a trap zone that attacks intruders, but Shadow X, who appears damaged, intervenes to protect Teppei from Metal Face's ambush. Afterward, they examine Shadow in Hokuto's lab and discover she was handmade outside the Machine Empire. They find a clue linking Shadow to Kamui Island and Karen. After enhancing Shadow's systems to enable communication, they learn she refers to X as her "big brother." X instructs Shadow to return to Kamui Island and protect Karen while they proceed to The Area. Metal Face eventually confronts Teppei and X again, but Teppei's Shining Knuckle easily overpowers him. Teppei emphasizes the importance of relying on one's inner strength rather than machines, and X conveys to Madonna that B'ts have their own hearts and decisions. As they leave, Metal Face vows revenge against Teppei.

Teppei and X are attacked not long after leaving Metal Face. Arrows are appearing from out of nowhere! Then Ron and Raido, Fou and Je'taime, and Hokuto and Max show up and start attacking them! Or are they...? ^___^ Evil Meimu and his B't Halloween are masters of the nightmare. They have already started working on Teppei and X! Just as the fight between them is getting started, Metal Face and his B't Madonna show up again! Metal Face starts screaming that HE is the only one who is going to kill Teppei. He needs it and he wants it. (Told ya, he was obsessed!) Meimu is annoyed and attacks Metal Face and Madonna and Teppei and X end up rescuing them from Meimu!! Madonna is fatally injured in the battle and crash lands. Meimu attacks Teppei with his ""Final der Mogliche"" and his B't Halloween sends him into the ultimate nightmare of ""Dark Inferno""! Are Teppei and X going to be able to win this one?! Episode summary graciously provided by Vortex Fansubs

Teppei wakes up in a nightmare... Meimu tells him that if he wants to escape, he must defeat the monster. Yet, every time he defeats the monster, it comes back stronger! What can he do? The damage he is taking is affecting his real body and he'll soon die if he doesn't escape! Meanwhile, Halloween has attacked X and he is now injured and lying helpless on the ground. After many attacks, it appears that Meimu has won. Teppei is not able to defeat the monster... As he's dying, he hears X... X is calling for him! X offers his life so that Teppei can burn his Piece of the Sun and break free. Teppei says NEVER AGAIN! He has only his life left and that's the one he'll use. As Meimu's monster comes in to finish him, Teppei ""powers up!"". The monster doesn't stand a chance and is blown away by Teppei's brilliance, which destroys the Dark Inferno. X catches Teppei as he falls and Halloween attacks them! Teppei is still unconscious, so there's not a lot X can do. Madonna gathers h