The Ultimate Trump Card

Saikyō Saikō no Kirifuda (最強最高の切り札)

As Prince Zanac rallies the citizens, the Adventurer Coalition moves into enemy lines to rescue the captured civilians in the residential sector, while the royal guards hold back a wave of demons until Momon is dropped in by Nabe and Evileye to be rid of the monsters. Momon urges the guards to move to protect the Re-Estize citizens who are vulnerable.

Brain, Climb and Lockmeier use the battle of the adventurers and demons to investigate the warehouse area for captured civilians, Brain manages to spot a disguised Shalltear and goes to battle her in order to give his comrades time from the monster. Upon encountering the vampire, Shalltear is unable to remember him due to her resurrection; but Brain takes it as she can't remember him since she views him as insignificant. Brain uses his Field martial art, and Shalltear walks into it, but this time Brain's new mentality from Sebas allows him to aim for and cut her fingernail with Four Fold Slash of Light, a weakened version of Gazef Stronoff's Six Fold Slash of Light. 

While Shalltear is mildly impressed calling him a "Nail Clipper," Brain is overjoyed, realizing he has reached a new level of strength from having his friends in his heart. He then runs, but Shalltear notices Climb and Lockmeier, remembering the order from Demiurge gave her. So she lets them flee; Brain tells them while hiding that Shalltear can match Sebas in strength, and he successfully cut her fingernail. While Brain knows the meaning of this, Climb and Lockmeier hesitantly congratulate him. They use this chance to continue running.