Kazuma and Aqua visit a magic shop run by a kind-hearted lich named Wiz, who reveals herself to be one of the Demon King's generals in charge of protecting a barrier surrounding the Devil King's castle. After Wiz teaches Kazuma the Drain Touch skill, the party takes on a request to exorcise evil spirits from a mansion, where they can stay during the winter. Later that night, Kazuma and Megumin find themselves on the run from an army of possessed dolls while also desperately needing the bathroom. The following morning, Aqua reveals that her actions after first meeting Wiz led to the mansion being haunted in the first place.
Keele's Dungeon Exploration with just Kazuma and Aqua
Wiz was introduced earlier in the first light novel, but we only see her introduction here as a short flashback.
In the LN, Wiz also mentioned there is only one Demon General that she is close friend with.
However, the anime did make several minor changes to the Mansion scenes and bring out more character developments:
In anime, Aqua went on an extremely long monologue describing all she knows about Anna. That continued even after others had cleaned up the mansion and settled in.
For the scene in Aqua's room, they changed dialogues between Kazuma and Megumin slightly. In the LN, Megumin is more cooperative. However, in Anime, she basically threaten to sabotage Kazuma, if he tried to pee from the balcony.
In the LN, for the bathroom crisis scene, Kazuma went first and later sang outside of the bathroom for Megumin upon her request.