Asta and Liebe vs. Lilith and Nahamah

Asta and Liebe vs. Lilith and Nahamah is a fight that occurs in the Spade Kingdom Castle.

Pre-Fight
After breaking out of Nacht Faust's Monument of Atonement, Lilith and Nahamah restrain his arms with Demon Ice and Demon Fire Magic, which causes Nacht to scream in pain. They want to kill him and hear his final scream, so Nahamah reaches for Nacht's throat. Fortunately for Nacht, Asta in his Unite form bursts into the room and severs Nahamah's hand. Nacht insists that Asta leave him and fight the Dark Triad, but Asta refuses and removes Nacht's restraints. Asta then tells him to live and see the strength that he cultivated.

Fight
The marking on Asta's chest changes, so he freaks out that he only has four minutes left in the form. Nahamah looks at its right arm and shivers with excitement as it has not faced anything so entertaining for centuries in the underworld, while Liebe is looking forward to facing the highest-ranking devils from his childhood. Nahamah and Lilith trap Asta in a twister of fire and ice, but Asta cuts through it and tries to behead Nahamah. The devil disappears into its own magic, evading the strike. Nahamah and Lilith both launch projectiles at Asta and debate which of them will hit and kill him first. However, Asta pulls out the Demon-Destroyer Sword and neutralizes the devils' magic. He then brings the Demon-Slayer Sword down on Nahamah, cutting through the devil's body.

Lilith freezes Nahamah's body and then fuses their bodies together, while laughing at Nahamah's loss and the prospect of continuing to play together. The fused devil wishes to hear Asta scream, but when he admits that he cannot feel their power, they unleash huge columns of fire and ice, which Asta cuts through. The devil then flies high above the castle and creates a massive freezing sun in order to cause Asta pain from the deaths of everyone below. When they launch the sun at the castle, Asta increases the size of his Black Divider and reflects the sun back at the fused devil. They merge into their sun, so Asta cuts it open with the Demon-Dweller Sword and then flies into it.

Inside the sun, the fused devil unleashes torrents of magic, but Asta neutralizes their magic again. Liebe appreciates Asta's help in making the lowest-ranking devil strong enough to take on highest-ranking devils. No longer enjoying the fight, the fused devil begins to feel a foreign emotion, which Liebe correctly surmises is fear. The fused devil notices that Asta only has one minute left so they flee from Asta to wait for his transformation to end. Asta cannot keep up, and after gaining some distance, the fused devil gloats and proclaims that they will crush him, his companions, and all humans. However, Nacht emerges from their shadow on an ice chunk behind them, and restrains them long enough for Asta to close the distance. Asta swings two swords in a cross chop, which cuts the devil in several pieces.

Immediately after, Asta and Liebe reach their time limit and split apart. As they fall, they cross their marked wrists in celebration.

Post-Fight
The fused devil's body then disintegrates, but their magic continues to cover the castle. Nacht catches Asta and Liebe and brings them to a roof of the castle. There, Asta begins to suffer the full-body pain from using Unite and explains that he will not be able to use Unite or his black form for 30 minutes.