Mugen Train arc (無む限げん列れっ車しゃ編へん Mugen Ressha Hen?) is the seventh arc of Kimetsu no Yaiba.
The entire arc serves as the basis for Kimetsu no Yaiba: The Movie – The Infinity Train .

Synopsis
After Enmu is tasked with killing Tanjiro Kamado in order to become a High Rank and get more blood from Muzan , Tanjiro, Zenitsu, and Inosuke buy tickets for the Infinity Train in search of Kyojuro Rengoku , the Flame Hashira. Tanjiro hopes he has information about the Hinokami Kagura.
Kyojuro informs them that he has been sent on a mission to kill a Demon suspected of being the cause of multiple disappearances on the train. He informs Tanjiro that unfortunately he doesn’t know anything about the Hinokami Kagura. He quickly detects a demon and kills it, the group, impressed by his skills, ask him to make them their Tsugukos and Kyojuro agrees.

The trio and Kyojuro fall asleep and Enmu asks for help from five civilians on the train who are suffering from severe insomnia. One of them is the train driver, who follows Enmu to dream of his dead wife and child. Enmu promises to use his powers to give each of them comforting sweet dreams in exchange for their help in completing his plan to kill the Demon Slayers. The group has already touched Enmu’s blood by grabbing their tickets, thus enacting the first act of the plan.
The driver is put to sleep as a reward for his work, and the other four are sent to carry out the rest of the plan.
While sleeping, the band members have strange dreams after touching the tickets. Zenitsu dreams that he has a date with Nezuko, Inosuke dreams that he is a “cave explorer” with Tanjiro, Zenitsu, and Nezuko as animal servants, and Kyojuro dreams of his brother and son’s progressive depression. father as well as how it affects the family. Meanwhile, Tanjiro dreams of being reunited with his family again.

Enmu’s minions strive to connect to the group’s dreams using a rope and a special spell that allows them to enter the dreams of others, completing the second stage of Enmu’s plan.
Due to the nature of Enmu’s powers, the dreams that are shown to a person exist in a limited space, with the outside being an unconscious area where a person’s “spiritual core” resides. The unconscious area is described as an extension of the type of person one is, practically a metaphorical representation of who one is and what one is as a person.
Before Kyojuro can see his “spirit core” destroyed (which would render him unable to move, think, or feel, thus becoming easy prey), his body subconsciously shifts and holds the person bound to his dream by the neck. , preventing any damage to its core. However, since he can’t kill humans, Kyojuro can’t go any further, which puts them both in a bind.
Meanwhile, Tanjiro pursues his dream while receiving more and more unconscious signals from his mind, such as seeing Nezuko’s box or being told by himself in his Demon Slayer uniform that he is live a dream.
At the same time, Nezuko wakes up and comes out of her box, having been confused by Kyojuro ‘s actions before attempting to wake Tanjiro but to no avail. Annoyed, she headbutts Tanjiro but ends up splitting her head open and begins bleeding from Tanjiro’s comically hard forehead. She then used her Blood Demon Art, which engulfed her real body and her dream body in flames, which allowed her to slowly wake up and retrieve her sword and uniform.

Battles and Events
- Demon Slayers vs. Enmu
- Kyojuro Rengoku vs Akaza