Four hundred years in the past, a group of guests as a hot spring and an inn recently built around it discuss its owner's good fortune at finding the hot spring. Meanwhile, the inn's owner, Kahei, refuses to allow a woman named Tami to marry his son Yohei despite them already being engaged. As Tami leaves distraught and furious at the news, Kahei talks with Yohei and a new bride-to-be named Hanae about their now-upcoming wedding. He explains that this new marriage was arranged due to Hanae's family running their own hot spring inn and her resulting experience in the business. Elsewhere, a samurai is attacked on the road by Wanyuudo, who haunts the place. As he sends the samurai falling from the cliff, he yells that he can still run. The next day, Ai overhears rumors about Wanyuudo while disguised as a worker at a local inn and travels on the road that night in hopes of getting Wanyuudo's attention. Wanyuudo is surprised by her lack of reaction to him and demands to know why she doesn't fear him. He calms down when Ai asks if he's really that intent on frightening people. He calms down and they talk about his origin as the wheel of a carriage that crashed in that area, killing everyone on board, and how bitter he is about it. When he says that he'll keep running until he winds up in Hell, Ai asks him to go with her as she knows something of Hell. At her urging, Wanyuudo takes the form of an old man. They introduce themselves properly while walking the next day.
In the present day, Wanyuudo visits that resort that now exists on the site of Kahei's inn and comments on how much it's changed over the centuries. As he relaxes in the spring, he is interrupted by a trio of high school students led by a girl named Ichiko, who is called back inside for dinner by the resort's manager before she can reveal something to him.
In the past, Ai and Wanyuudo stay as guests at the inn and Ai reveals the existence of the Hell Correspondence, which in that time period takes the form of black ema
left at a shrine. That night, Kahei, Yohei, and Hanae treat the two to a lavish meal as they are the family's first guests without any relation to the local officials. Later, Ai brings Wanyuudo to a local shrine to show him one of the black ema.
In the present, the resort's manager, Yurie, relaxes in the hot spring, but is interrupted by Ichiko. Ichiko forces Yurie to walk back to her room naked for serving a meal she didn't like and further blackmails a large amount of money from her. As soon as she returns to her room, Yurie accesses the Hell Correspondence.
Back in their room in the past, Wanyuudo asks if there are people who would actually use the Hell Correspondence knowing what it entails. Ai says that there are and the two return to the shrine, where Tami has placed an ema with Kahei's name. As Ai lays out the terms of the deal, Tami tells Ai that she is seeking revenge because Kahei selfishly turned her away when she was not only engaged to Yohei, but pregnant with his child. Tami pulls the thread immediately and Ai takes Wanyuudo to the sunset world. When Ai reveals that she travels to vengeance targets on foot, Wanyuudo transforms himself into a carriage to make her job easier and the two ride forth to claim Kahei's soul. Kahei finds what he thinks is a second hot spring outside his inn, but finds the water to be boiling. He then is swept away by a wave of water into a much larger boiling hot spring. Ai ferries Kahei to Hell and Yohei and Hanae find his scalded corpse the next day.
In the present, Hone Onna visits Wanyuudo in the hot spring and remarks that fate seems to have a sense of humor as Ichiko is Tami's descendant while Yurie is Hanae's. Having had enough of Ichiko's blackmail and abuse, Yurie pulls the thread of Ichimoku Ren's straw doll form. Ichiko finds herself in a red-tinted version of the resort's lobby, which is flooded by a boiling hot spring. The hot water melts Ichiko's clothes away and she runs outside, only to find herself standing on a cliff overlooking another boiling hot spring. She backs into Ai's minions, who jump into the water with her in tow. Ichiko is then swept away by a wave of boiling water.
Back in the world of the living, Yurie explains that the resort is being forced to close because Ichiko had blackmailed her with the knowledge that the resort had been artificially filling the hot springs after they dried up some years before. Ichiko had told her friends to reveal that information to the media if anything happened to her. When Yurie tells Ai and Wanyuudo that they are the resorts last guests. Wanyuudo comments that that means its first guests are its last.
In the past, Ai tells Wanyuudo that just as it was in his nature to run through the mountains, humanity will never stop hating. She then asks him to come with her. Wanyuudo says that he doesn't want to be an attendant. Ai tells him to instead be her legs, which Wanyuudo happily agrees to.
In the present, a candle with Yurie's name is lit.
This episode contains examples of:
- Arranged Marriage: Kahei saw his son's marriage to Hanae (and cutting of Yohei's marriage to Tami) purely as a business arrangement. While that was a common practice around the world at the time and Yohei and Hanae seemed to be happy together, it was still an incredibly selfish thing to do.
- Blackmail: Ichiko found out that the resort was keeping the hot spring going artificially and used that to force Yurie to do any number of things for her. She was also savvy enough to make sure her friends knew in case anything happened to her. Yurie sends her to Hell after having enough of the abuse and realizing that Ichiko was probably going to tell the media anyway.
- Character Focus: Wanyuudo's backstory takes center stage in this episode and Ai's work in both time periods is viewed from his perspective.
- Dark World: Both of the Afterlife Antechambers in the episode are heavily red-tinted versions of the inn in their respective time periods with lots of boiling water added in.
- Godiva Hair: Ichiko winds up with this during her Hell-banishment.
- Hot Springs Episode: Ai and Wanyuudo visit a hot spring resort two different times four centuries apart for very similar reasons.
- Humanity Ensues: Downplayed. Wanyuudo first disguises himself as a human with Ai's encouragement.
- No Body Left Behind: Kahei is the sole aversion of this trope in the series. In other episodes, people are dragged bodily from the world of the living. Here, Kahei's scalded corpse is left behind for his son and daughter-in-law to find, presumably because Ai would have had some difficulty disposing of it on her own.
- Red Sky, Take Warning: More like red everything take warning, though the sky in the Hell-banishments is a brighter shade than anything else in those scenes.
- Shameful Strip: Ichiko forces Yurie to do this in retaliation for a meal that wasn't to her satisfaction. This later gets turned back on Ichiko when her clothes are melted off by boiling water.
- Skintone Sclerae: Wanyuudo's human form is revealed to have this feature, his backstory being the one time in the series that they're not perpetually closed.
