The Challenge to the Past - S1.E5

Sakuya meets up with Shiori again and informs her that Karasuma's body was fake and set up to burn. Amane insists on going to a cave where people can supposedly hear the voices of the dead. She convinces Kotaro and Kazuma to take her, but when they get there, she's poisoned by the Centipede Undead. Upon hearing this, Hajime rushes to find the Undead. He tells Kazuma that they can get the antibody from the Undead but only if it's alive. Garren hunts down the Undead and fights it until Chalice and Blade appear. Chalice fights the Undead while scanning its body for the antibody and Blade fights Garren to prevent him from killing the Undead.