How NOT to Summon a Demon Lord — Season 2

Diablo inadvertently rescues the priestess Lumachina Weselia from an assassination attempt. As Lumachina had been praying when Diablo appeared she now believes Diablo is God.

When the group arrives in Zircon Tower City, a child named Horn offers to be a guide to the dungeon; the description confirms it is Diablo's dungeon. Later, a monstrous sand whale attacks the city and Diablo tries to fight it, but requires the help of Batutta and the city's leader, Fanis Laminitus.

Lumachina and Rem are drugged and abducted by Batutta and his maid, Shiliu. Horn spied on them and warns Diablo and Shera.

The group arrives at Diablo's dungeon and have to go through several rooms filled with mazes, monsters and lava.

Diablo saves an unconscious Horn and sacrifices his shirt and cape to make a fire. Rem, Shera, and Lumachina get through several floors of the dungeon only to run into Gewalt, who attacks them. They are interrupted by a massive black dragon who attacks them all.

Zircon Tower City's defenders are no match for Varakness' army. Varakness attempts to force Fanis to marry him. Diablo takes offense to Varakness saying he is working for a Demon Lord, so his group, including Rose, teleport to the battle. Diablo, Shera, Rem, and Rose then battle the army while Lumachina heals the injured with Horn assisting her.

Lumachina asks Diablo to accompany her to the royal capital, so he decides to stop by Faltra City on the way. Diablo`s group is worried about Klem and Edelgard after such a long time apart, and Sylvie informs them that they`re at a bakery. Apparently the Fallen, Edelgard, had started a part-time job. Curious, Diablo and the others go to investigate...

Diablo and his group arrive at the royal capital, Seven Wall, but the guards stop them at the gates. That explosive situation is resolved by the imperial knight, Alicia. She was awaiting their arrival and leads the group to an inn. That night Diablo reveals to Alicia that the church is out to kill Lumachina.

As Horn feels torn between escaping and wanting to rescue her friends, a tiny goddess appears and says she can substantially raise her levels. 

After Diablo incurs heavy damage rescuing Lumachina from Europa's destructive attack, he asks her to cast a spell that will remove Europa's barrier.