Flame Hashira Kyojuro Rengoku receives new orders: Travel to the Mugen Train, where over forty people have gone missing, and conduct an investigation. Leaving the Demon Slayer Corps Headquarters, he sets off on this new mission.
In the dead of night, a conductor walks around the carriage of a moving train. As he ensures it is empty, the lights flicker; he turns and sees a marked demon hiding in the shadows. As he attempts to flee, he is rapidly killed and his body is discovered later.
A demon slayer enters a soba shop, guided by a Kasugai Crow. He enters and sees the Flame Hashira, Kyojuro Rengoku, enjoying a bowl. Apologizing for interrupting his meal, Kyojuro offers a seat and asks the chef to give him a bowl as well. The two discuss an incident last night, where they discovered an injured woman, attacked by a demon but recovering in hospital. Kyojuro asks the chef on how business is, to which the chef responds everybody is afraid to be outside after dark, with word of a slasher going around, even forcing him to let off his workers. He adds the news of the Mugen Train being put out of service, after 40 of its passengers had mysteriously disappeared. The demon slayer informs the Hashira the Mugen train has been located and they leave to investigate.
In a train station, a young girl, Fuku, struggles to feel better after no one buys her bento boxes, due to the place being completely empty. Her grandmother tries to cheer her up by claiming she can sell instead during the afternoon, as demons only roam around at night. The demon slayer and Kyojuro search around the station but find nothing unusual. Instead, they witness Fuku irritably dissuade her grandmother's advice about demons, claiming they don't exist. Kyojuro approaches her and bluntly claims he is looking for a demon, to the shock of the accompanying demon slayer. Fuku angrily claims there is no demon and hurls her bean bun at Kyojuro, smacking him in the face. Fuku apologizes and states she feels so on edge with the news of the Slasher affecting everyone. Kyojuro advises them to continue business and claims he will deal with the Slasher. Fuku tries to sell him some bento boxes, to which he excitedly decide to buy them all. He gives them to the demon slayer, telling him to return to the headquarters and claiming they will make great gifts for the Demon Slayer Corps.
Kyojuro boards a train with a crate of bentos and is happened upon by an annoyed conductor. He claims to be a bento vendor and is looking for the Mugen Train's shed, believing the train he is on will take him there. The conductor corrects him by stating the Mugen Train's maintenance facility is in fact a fair way in the distance. The Flame Hashira thanks him and states this is now where he will disembark, before leaping off the train and running towards the facility. He enters and sees the train being repaired, before sensing the faint scent of a demon lingering on it. A worker asks why he is trespassing onto the facility, to which Kyojuro states he was sent to give food to the workers. As he passes the boxes around and the workers eat, Kyojuro asks why the Mugen Train is here, where he is told the train is claimed to be a "man-eating train". However, the worker informs him the train is actually slated to be put back in service after the repairs are made, worrying him. Suddenly, someone screams, forcing Kyojuro into action as he investigates what has happened. He sees the marked demon, holding a young boy, Tatsu, in his hands and driving his claws in. The workers follow and are horrified seeing the demon clutching their friend. The demon wretches, before stomping on a dropped bento box and claiming human food is repulsive to him. As the Hashira confront hims for stepping on it, the demon digs into the boy's flesh deeper and responds that he only devours humans that "seem tasty" and harms those who he find disgusting. Suddenly, his markings glow, and he speeds around Kyojuro and tries to goad him into attacking. The scene forces the other workers to flee in terror while Kyojuro stands his ground.
The demon claims he is the fastest and taunts him, claiming he can't kill him without injuring the boy. He also mentions that last night, he had slashed a woman till he became bored, making Kyojuro realize it was him who had injured the woman he had found. He commends the demon for his speed but warns him to be get cocky, and the Hashira tells him the woman was in fact saved and is determined to heal without even lasting wounds. Instead, the demon decide he will now kill the vendors who gave him the bento boxes in place of the woman. Before then, he decides to kill the young boy, but Kyojuro rushes forward and slices off both his hands, saving him. The demon retreats and stands outside the shed, before smelling the likely station the vendors are at and speeding forward to kill them.
Kyojuro treats the boy's wounds before calming the concerned workers by stating his friends will arrive, to which more demon slayers arrive to assist him. Meanwhile, Fuku and her grandmother have arrived at the station and Fuku is begins setting up shop. The demon arrives shortly after and smells them nearby. Kyojuro leaves the rest to them and follows the train tracks, using Total Concentration Breathing to accelerate him to incredible speeds, determined to stop the demon and save them. The demon finds Fuku and moves forward to kill her, but is hit by a bento box thrown by her grandmother. With the demon momentarily disgusted by the smell, Fuku attempts to flee outside but is quickly caught, the demon viciously grabbing the young girl's throat. Before he can kill her, Kyojuro arrives and slices the achilles heel of the demon, saving Fuku. Stunned by what she had just witnessed, Fuku realizes her grandmother is now alone.
The demon confronts her for throwing the bento box but is instead accosted by Kyojuro. Wondering how he had caught up to him so quickly, the Hashira repeats his words about not getting cocky. The demon challenges him on who is faster; whether he can kill Fuku's grandmother first or Kyojuro decapitates him before. To this, Kyojuro claims he is slow and he instantly rushes forward, decapitating the demon with the Flame Breathing, First Form: Unknowing Fire. After decapitating the demon, Kyojuro performs a process of Chiburi (flicking any blood or liquidy substance off the blade of his Nichirin Sword), dragging the blunt-end of the kissaki toward the koiguchi-mouth opening of the scabbard and sheathing the sword through Nōtō. The scene suddenly reminds Fuku's grandmother about an incident 20 years ago; she herself was protected from a demon by the previous Flame Hashira. She was saved, along with her daughter, Fuku's mother, and is soon driven to tears after seeing Kyojuro's haori and witnessing him sheath his blade in the same way her previous saviour had.
She tearfully mentions this to him, to which he responds that it was most likely his father, Shinjuro Rengoku, who saved her. He is simply following in his footsteps to save people from demons. Fuku apologizes to her grandmother for not believing in demons, to which Kyojuro laughs and responds that not believing they exist is for the better. Other demon slayers arrive at the scene, to which Kyojuro informs them the demon has been dealt with. He adds that the Mugen Train is being repaired tonight and will back in service the next day. When his companion claims the situation is now over, the Hashira tells him the Mugen Train had 40 people go missing, and the demon likely responsible is not the one he had just killed. He believes the train is harboring a far more powerful demon. The sun rises to a new day and people now swarm the streets; the soba chef overhears news the Mugen Train is back in service, hoping nothing odd happens again.
As the sun sets, Kyojuro boards the Mugen Train for his investigation, but not before meeting Fuku and her grandmother again. They offer him beef bento boxes in gratitude for saving them; he happily takes them, as they are not the one he tried before. He takes her entire supply and they wish him good luck on his mission. As the train prepares for departure, Fuku sells some bento boxes to the passengers but hears a loud commotion nearby; Inosuke Hashibira head-butting the train and Zenitsu Agatsuma angrily accosting him. Inside the train, the passengers prepare for the trip; Kyojuro decide now is time to eat the bento box, to which he opens the package and tries his meal, before loudly exclaiming it to be delicious.
Characters in Order of Appearance
- Episode 27 is entirely anime original. It appears to take place during the events of Chapter 53.