Talk:Demon Slayer: Kimetsu no Yaiba – The Movie: Mugen Train/Plot

Plot

Tanjiro Kamado, his sister Nezuko, Zenitsu Agatsuma, and Inosuke Hashibira board the Mugen Train to assist the Flame Hashira Kyōjurō Rengoku in his mission to hunt for a demon that has caused forty people to go missing. Soon after boarding, all of them are enchanted and fall into a deep sleep. Enmu, Lower One of the Twelve Kizuki, instructs four passengers, all suffering from severe insomnia, to enter the Demon Slayers' dreams and destroy their spiritual cores so that they can't wake up again. In exchange, Enmu will grant them a peaceful sleep.

During their sleep, Tanjiro and his companions have happy dreams; Tanjiro reunites with his deceased family, Kyōjurō reminisces on his past with his younger brother and disapproving father, Zenitsu envisions a quiet life with Nezuko, and Inosuke imagines himself as an adventuring leader. The girl who invades Kyōjurō's dream locates his core, but his immensely strong spirit manages to halt her even while still unconscious.

Tanjiro realizes that he is dreaming, tearfully abandoning his family and tries to wake up, succeeding after a vision of his father instructs him to kill himself in the dream. At the same time, Nezuko uses her Demon Blood Art to sever the intruders' connection to the slayers, and awaken the passengers. In fear of Enmu, they attack Tanjiro, who knocks them all out, except for his intruder, who had grown incredibly guilty after uncovering his subconscious and discovering he possesses a pure heart.

While Nezuko awakens the others, Tanjiro confronts Enmu on top of the train, who becomes overjoyed to discover he is the "man with the Hanafuda earrings" that his master, Muzan Kibuzuji, desires killed. In the ensuing battle, Tanjiro beheads him, however, Enmu reveals that he fused himself with the train, preparing to devour all the attendants within. An awakened Kyōjurō instructs Inosuke and Tanjiro to look for Enmu's neck while he, Nezuko, and Zenitsu stay behind to protect the other passengers. Tanjiro and Inosuke find Enmu's neckbone in the engine room, but are caught off guard by its defenses, including its Blood Demon Art that constantly puts him to sleep. The conductor ends up stabbing Tanjiro in the chaos, but together with Inosuke, they are able to expose Enmu's neckbone, killing him and derailing the train. In the aftermath, Enmu laments his failure over being defeated by the Demon Slayers, disintegrating away.

As Tanjiro attempts to recover from his wounds, Kyōjurō arrives to help teach him how to stabilize it with his breathing techniques. However, they are suddenly attacked by Upper Three of the Twelve Kizuki, Akaza, who tries to persuade Kyōjurō to turn into a demon to become immortal, after sensing his already immense power. Kyōjurō easily refuses, thinking about how his mother taught him to always use his strength and gifts to protect others.

Kyōjurō orders Tanjiro and Inosuke to stand back, while he and Akaza commence in a fight to the death which the others can barely keep up with. Despite his perseverance, Kyōjurō is unable to match Akaza's regeneration skills, as the demon manages to fatally injure him by piercing his stomach. Kyōjurō attempts to keep him at bay for long enough for the sun to kill him, but Akaza manages to break free and escape. In a last ditch effort to stop him, an enraged Tanjiro throws his sword at Akaza, which impales the demon's chest, but he still manages to get away, as Tanjiro breaks down calling him a coward.

Kyōjurō succumbs to his injuries and encourages Tanjiro and his friends to continue on his path, before dying. The three are devastated over the death, with Tanjiro especially drawn into despair due to the nearly impossible power gap the Demons have revealed capable, but Inosuke reminds him to heed Kyōjurō's last words and keep fighting to get stronger. The remaining Hashiras receive the news of Kyōjurō’s death, while the head of the Demon Slayer Corps, Kagaya, appreciates him for not letting a single passenger or comrade die in his presence, stating that he will be glad to reunite with him when he finally passes.