Warning: Spoilers ahead.
Continuing right after Demon Slayer: Kimetsu no Yaiba Mugen Train Arc TV Episode 3
is struggling to get out of his dream. A vision of his father
gives him a hint to get out. Would have been kinder to straight up say how to get out, but I get it. Dramatic effect. Tanjiro has to kill himself in his dream to wake up. He doesn’t know that as a fact, could be the wrong move. Just following a hunch.
But it pays off and he wakes up. But right before that moment, the kid inside his subconscious is looking for the spiritual core. The incarnations of Tanjiro are so kind, they lead the kid to it. Even though he wants to destroy it. The kid is moved.
The other kids that Enmu is controlling are in the subconsciouses of Inosuke, Rengoku and Zenitsu. Inosuke and Zenitsu have discovered their presence and their defenses are up in the dreams. It’s hilarious!
Anyways, Tanjiro wakes up and discovers Nezuko has burned off his connecting rope with her demon blood. She’s so darn cute when she’s little! He has Nezuko burn off the ropes on the other Demon Slayers, too. But they don’t wake up just yet.
The kids confront Tanjiro. They want to go back to their happy dreams. Tanjiro sympathizes, but he won’t let them stop him. He knocks them all out with a karate chop. The only one still standing is the kid in his own dream, who no longer wants to go forward with Enmu’s scheme. He touched Tanjiro’s heart, and it was so pure, he changed his ways!
Tanjiro can smell Enmu. He gets on the roof of the train and confronts Enmu at the front of it. We learn a little more about Enmu’s powers, how he uses a remote Demon Art to put the Demon Slayers to sleep from a safe distance. He doesn’t understand how Tanjiro escaped from the dream.
Tanjiro moves to attack Enmu with his Water Breathing techniques. But Enmu is able to put him to sleep by saying the spell out loud and aiming his creepy hand at Tanjiro. Tanjiro falls asleep, but only a split second before waking up again and continuing his assault on Enmu. Finally Enmu realizes that Tanjiro keeps killing himself in the dreams to wake up - which takes tremendous willpower. Enmu is shocked by this.
Finally Tanjiro’s strike connects and he chops off Enmu’s head! Unfortunately, this body wasn’t the real Enmu. The real Enmu has fused with the train, so that Enmu IS the Mugen Train. He manifests as this creepy living purple blob thing.
Enmu threatens to devour all the passengers inside. Tanjiro can’t protect all of them, so he rushes back to the Demon Slayers to wake up them up. Luckily Nezuko’s blood has woken up Inosuke. He slices and dices and destroys things as soon as he awakens!