WARNING: The following contains spoilers for Episode 5 of I've Been Killing Slimes for 300 Years and Maxed Out My Level, now streaming on Crunchyroll.
Azusa Aizawa, the famed Witch of the Highlands in I've Been Killing Slimes, can take on any challenge and win with her superior magical power... except when it comes to the paranormal. Azusa has been making powerful friends left and right, forming her own squad of superpowered allies, but in Episode 5, when her elf friend Halkara comes to her for help with a spirit problem, Azusa finds herself outmatched. She simply can't stand ghosts.
Halkara was looking to set up a factory nearby and hire some employees, but quickly discovered her supposedly empty factory has a ghost problem. Like Azusa, Halkara doesn't dare face the ghost head-on, but help arrives in the hellish form of Beelzebub.
Azusa uses a summon spell to bring her demon friend Beelzebub right into her house, though her aim is a bit off and Beelzebub appears in a bathtub filled with cold water. After drying off, she agrees to help Azusa and Halkara with their ghost problem. Once it's evening, the three girls visit the dark, empty factory and wander its halls, waiting for the ghost to show itself. Beelzebub finally sniffs it out and captures the ghost in a break room. The ghost is revealed to be the apparition of a young woman named Rosalie. And prior to becoming a ghost, she did not die a happy death.
Rosalie had an arranged marriage a few centuries before the time of I've Been Killing Slimes' story, which only benefitted her scheming parents, and in desperation, she tragically ended her own life inside a house that once stood where Halkara's factory now is. Rosalie is bound to that location, but Beelzebub has a resourceful idea: have Rosalie possess Halkara, then walk away in that mortal shell and escape the factory. The plan works, and Rosalie finally escapes the factory. But now there's a new issue: Rosalie is stuck in Halkara's body, and the longer she stays, the more likely Halkara's body is to die from the strain of housing a foreign spirit.
Rosalie's spirit is stuck tightly in Halkara's body, due to their high compatibility, so Azusa and her friends try everything to shake Rosalie's spirit loose. They even try scaring Rosalie out of the elf's body with Laika's dragon form and performing an exorcism at a local church, but it's all a bust, and no magic on Azusa's or Beezebub's part works. Then Beelzebub realizes something: earlier, she had gotten a shock from being summoned into that tub of freezing water, so why not try that? Once Rosalie's spirit is finally put to sleep and Halkara's takes over, Beelzebub tosses Halkara's body into the tub. That shock, combined with Halkara's spirit being awake, helps get Rosalie loose at last.
Now free, Rosalie promises to not haunt the factory any longer, yet the rumors about her will likely scare off any potential employees -- definitely not good for Halkara's prospects. So, Azusa encourages Rosalie to make herself known to the townsfolk and help them out, cleaning up and running errands with her telekinetic spirit powers. Now Rosalie is the friendly neighborhood ghost, and Halkara can get her factory up and running. Azusa had never seen a ghost before, but the world of I've Been Killing Slimes is full of surprises, and Azusa is clearly perfectly capable of adapting.
