Episode 12

TL;DR

Cain fights Aaron, who transforms into a dragon, with the help of Seth and his subordinates. After a fierce battle, Cain uses his powerful "Saint Sanctuary" magic to defeat Aaron, ending the monster onslaught. The king rewards Cain with the title of Viscount and the domain of Dorinthol. Cain takes charge of Dorinthol, despite the town's troubled history with the adventurer's guild. He confronts corrupt guild members, defends a waitress, and challenges the church's high tithes, even building a magnificent castle. Meanwhile, Cain meets Seth’s wife, Lefane, who rebukes Seth for infidelity.

Recap

Seth informs Cain that he and his subordinates will handle the onslaught of monsters while Cain focuses on defeating the ringleader, Aaron. Meanwhile, Nina, Millie, Claude, and Lina join the battle in the forest to support Cain. Seth's subordinates, shocked that their master has contracted with the God’s Chosen, begin subduing the rampaging monsters. Cain engages Aaron, who is in a weakened dragon form, and summons Haku and Gin to assist him. However, Aaron quickly overpowers Haku, and the rest of the group struggles against the endless wave of monsters until Tifana arrives with reinforcements.

During Cain's intense battle with Aaron, Gin shields Haku from Aaron’s devastating beam attack. Cain, determined to protect everyone, activates the powerful "Saint Sanctuary" ability, creating a massive pillar of light that annihilates Aaron and leaves a colossal scar on the ground. Seth and Dalmatia comment on Cain’s overwhelming display of power and confirm the onslaught has ended, securing the town's safety. Cain reunites with Tifana, Millie, and the others as Seth and Dalmatia take their leave.

Later, the king questions Cain about the massive pillar of light and the rumors of divine intervention. Cain explains that he used emperor-level magic when intermediate-level magic proved insufficient and admits that the Prince of Darkness aided him, shocking the king further. Overwhelmed, the king jokes about abdicating in favor of Cain but instead grants him the title of Viscount and the domain of Dorinthol. Cain enthusiastically accepts, despite the objections of Garm, Daim, and his fiancées, who warn that Dorinthol is plagued by corruption due to the adventurer's guild's abuse of power. Cain remains optimistic, eager to rebuild the domain into something new.
The king learns of Cain's tumultuous experiences in Dorinthol. Upon arrival, Cain is assaulted by the guild under the guise of a welcome party, which he easily defeats. In a pub, Cain defends a young waitress from abusive adventurers but is arrested by corrupt guards. Cain later confronts the church for demanding excessive tithes and eliminates both the guild and an underground faction planning to harm a priest. To cap off his actions, Cain constructs a castle even grander than the royal palace, leaving everyone astounded. While recounting his stories to Silk and Telestia over tea, Cain encounters Seth and his wife, Lefane, who reprimands Seth for his infidelity. After Lefane asserts her disdain for cheating, she and Seth reconcile and leave.