Head Priest

Head Priest is the overall thirteenth episode of the How NOT to Summon a Demon Lord series. It aired on April 9, 2021.

Synopsis
Diablo rescues Lumachina from Gewalt, then agrees to escort her to Zircon Tower.

Plot
Lumachina Weselia and Tria are fleeing through the forest. Tria knocks Lumachina out of the way of a Trap Worm, but gets devoured, horrifying Lumachina. Their pursuer, Gewalt, appears and mocks her, then summons a Beast Mushroom that uses its tentacles to strip and molest her. She prays to God for help, and he laughs and says her prayers are useless, but she glows with energy, then Diablo abruptly falls out of the sky and crushes the mushroom.

A few minutes ago, Diablo, Rem, and Shera were exploring when he decided to test a new spell. He makes a log levitate and rides it into the sky like a surfboard. As Rem and Shera are amazed, he notices the energy emitted by Lumachina and rides over to investigate. His spell wears off, causing him to fall out of the sky and land on the Beast Mushroom.

While he recovers, Gewalt yells at him for killing his creature, while Lumachina believes he is God who has come to save her because of her prayers, then freaks out because she is in a state of undress. He covers her with his cape and tries to explain that he is not God, but she insists that he is while Gewalt says he is just a demon. Diablo asks why a Paladin is attacking a girl and Gewalt says he doesn't know nor care; he's just following Vishos' orders. Gewalt summons a Hunter Worm, then has his Trap Worm ambush them by creating a pit where they would fall into its jaws. Diablo catches Lumachina and leaps out in time, then slays it with the spell Aero Shredder. Gewalt is amazed, but thinks the effort of doing that would weaken Diablo. Diablo says he can use spells multiple times, but Gewalt calls him a liar and summons several creatures. Diablo casts Cross Blizzard to encase Gewalt and his creatures in ice.

Lumachina praises "God" for his victory, then passes out due to the extreme cold. As he holds her, Rem and Shera arrive and become jealous, while he says it is not what it looks like and to help him. As they leave, an enraged Gewalt starts breaking free of the ice while the Trap Worm 's body shatters, exposing an unconscious Tria.

At the Peace of Mind Inn, Lumachina, now in a nightgown, asks Rem and Shera about their relationship with "God". Shera starts to explain that Diablo is their master, but Rem shuts her up and says Diablo is the leader of their adventuring group. Lumachina says he must be God, because if he isn't, then they must get married because he saw her bare skin. In another room, Diablo tells Klem and Edelgard to remain hidden until they learn who Lumachina really is. They hear Rem and Shera yelling in jealousy about the marriage comment and he enters the room. Lumachina asks if he is God. Deciding it would be a bad idea to admit he is a Demon Lord, he says must keep his true identity hidden, convincing her that he is God, but she agrees to call him Diablo, kneeling before him.

He asks who she is. She starts to glow intensely, surprising them, as she says she is just a woman who respects God, but she is the Head Priest of the Church. The Cardinal Vishos ordered her eliminated for investigating embezzlement and other corrupt activities in the Church. She mourns Tria, thinking she is dead, and explains she was planning to go to Zircon Tower to reach Batutta, a Paladin she believes is not corrupted. Diablo remembers his old dungeon from Cross Reverie is located there. Rem and Shera decide to help her and ask him for permission. Diablo wants to avoid conflict with the Church, but decides to help her. Klem and Edelgard enter the room, with Klem demanding more biscuits. Lumachina and Klem immediately become hostile as they can sense each other's holy and demonic energies. Edelgard tries to attack Lumachina, but Diablo stops her and orders them to cease hostilities.

The next day, they leave Klem and Edelgard in care of Mei, Sylvie, Celestine, and Emile. As Diablo, Rem, Shera, and Lumachina prepare to leave, Klem gives them a parting gift by supercharging Shera's bow with her dark magic.

Differences from the Light Novel

 * Tria gets chomped from her upper body instead of her lower body.
 * Lumachina's panties did not finally break away thus not exposing her "womanhood" to Diablo.
 * Diablo heard the girls’ conversation from outside the door. He keeps his identity hidden to avoid the marriage talks that Lumachina mentions.
 * Lumachina, Edelgard and Klem meet the same night that Diablo saved the former instead of morning of the next day.
 * Diablo intercepted Edelgard's attempt to strike Lumachina instead of him placing his hands on Lumachina and Klem's heads to defuse the tension when the two opposing forces meet.
 * Klem empowers Shera's bow at Faltra's gate instead of at the inn.