Ghost Sweeper: The Sword Princess and the Accompanying Rabbit (ゴーストスイーパー 剣姫とお供の兎) is a special story included in the limited edition booklet that was given out to people who bought both DanMachi Manga Volume 7 and Sword Oratoria Manga Volume 6 together.
One day in Orario, a rumor that the Sword Princess Ais Wallenstein failed a quest began spreading, and, as she was a First Class Adventurer from the Loki Familia, the rumor spread quickly, with many people theorizing what the quest could've been about. Bell was also concerned by the news, discussing the matter with Hestia, but didn't know what to do. As Lili and Welf were busy, he decided to go to the dungeon on his own, only to encounter Ais on the way there. Immediately, she requested for him to help her with her quest, confirming that the rumors were true. Feeling joy at the thought of her depending on him, he quickly agreed to her request, and she revealed to him that her quest was to get rid of ghosts in a mansion.
The two arrived at the mansion at night, which was an old dilapidated building. Soon after, she explained that a young Human girl had requested for her to get rid of a ghost from the building, which was her secret playground. She added that she had already attempted the quest once, nevertheless she ran out after seeing the ghost in the hall of the floor above her. At that point, Bell questioned why they had to come at night, to which she explained that her client had told her that the ghost only came out at night, and just as she pointed at the building they saw a shadow on the third floor that was wearing a black rag.
Upon entering the building, Ais drew her sword while looking around restlessly, causing him to ask if she was scared of ghosts, which she confirmed, stating that she couldn't kill them. Bell suggested that they head to the floor they spotted the ghost on, however she rejected his suggestion, mentioning that Riveria had once told her to keep the main part for last in times like these. Saying this, she locked arms with him as a precaution in case something happened, leading him to fantasize about her hugging him, though unfortunately for him she became scared when lightning fell and began squeezing his arm. Due to their three level difference, her strength crushed his arm, giving him intense pain.
Eventually, the two of them made it to the final room on the top floor. As they entered the room, they were frightened by the contents of the room, such as a bubbling cauldron and a magic circle on the floor, making them wonder if the room was being used as a sabbat. They reached their limit when a skeleton appeared from the shadows of the room, and immediately both of them ran out of the room, with Ais activating Ariel while she was still locking arms with him.
Later on, Fels complained to Ouranos that he had to move his atelier because someone saw him, and, noticing that he was reading a newspaper, asked what was so interesting. When he mentioned that Ais failed a quest, Fels recalled that she and Bell visited his atelier and had run off after they were surprised, causing Ouranos to make an expression as if he was enduring a headache. Several days after that, the girl came to thank the two adventurers as the ghost had seemingly disappeared, and as no one could guess what the quest Ais failed was, it became an urban legend.