While Izuku is telling everything to Nezuko, let's go to the subconscious of the other sleepers.

(Inosuke's subconscious)

A little girl is climbing away.

Girl: Where the heck's the spiritual core thing? This subconscious, I don't like being here at all. That topless boar-man I saw was also creepy. This is all so overwhelming.

Behind her was Inosuke...drooling he snarls at her and she freaks out and runs away. But eventually, Inosuke caught up to her and...I'm guessing ate her.

(In Zenitsu's subconscious)

It was pitch dark and the boy who was looking for the spiritual core was struggling to find everything. Or anything for that matter.

Boy: I can't see a damn thing in here. This sucks. What is with this blond brat's subconscious realm anyway? Do I really have to grope around like this to find his spiritual core? God damn it!

What he didn't notice was that the subconscious of Zenitsu was right behind him with a giant pair of scissors. He opens and closes them to get his attention.

Boy: What was that?

He snips those scissors again. And again. And then...

Ok...NOW he's scared.

Zenitsu: What the hell is a guy doing in this area? You parasite!

The boy gasps in fear.

Zenitsu: I only allow women in here!

Again, he snips his scissors. Causing the boy to start whimpering in fear.

Zenitsu: So I'm gonna kill you.

And the boy runs off screaming like a baby. But Zenitsu is right behind him.

Zenitsu: Where are the ladies?

Boy: WHAT?! HOW WOULD I KNOW?!

Zenitsu: Well, then...JUST DIE!

And Zenitsu continuously slices him up at the speed of lightning as the boy shrieks in pain. Until eventually, he gets killed.

(Inside Katsuki's subconscious)

Another boy was inside of his subconscious. However, there were far too many explosions and smoke to see ANYTHING.

Boy: Why are there so many explosions here? It doesn't make any sense.

Katsuki: Hey there you damn bastard!

Boy: What the-

He was met with an explosion to the face.

Katsuki: WHAT AN IDIOT! YOU REALLY THOUGHT YOU COULD DESTROY ME?! HAHAHAHAHAHA! YOU'RE EVEN DUMBER THAN THE REST OF THESE QUIRK REJECTS! (Demons) YOU REALLY THINK YOU CAN WIN AGAINST ME?! KING EXPLOSION MURDER GOD DYNAMIGHT?! WELL THINK AGAIN! HOWITZER IMPACT: CLUSTER!!!

Katsuki unleashes his most powerful move as the boy screams in fear and gets turned to ash.

(Back in the real world)

All three kids were sweating and struggling throught what was happening.

Izuku: ...And so, the stockpiling quirk, merged with Yoichi's quirk. And that's how my quirk, One For All, was created.

Nezuko: Wow. You know...that's pretty ironic.

Izuku: I know.

Tanjiro: Hang on...who are these people? They're tied to the others with rope.

He then noticed that the rope around his wrist was singed off.

Tanjiro: How is the rope singed off?

Nezuko: Since I now have a quirk that gives me the powers that I had before, I was able to use my exploding blood to burn the rope. I did this by banging our skulls together.

Izuku: Seriously, Tanjiro. How hard is your skull?

Tanjiro: No clue.

Izuku: My guess is that when our tickets were punched, we were put to sleep. However, the vestiges of One For All brought me to the vestige world just before that happened. That managed to save me. My guess is that this is the work of a demon.

Tanjiro: You have a point. But using such a strong BDA with this discreet of a smell...

Izuku: Smell?

Nezuko: Tanjiro has always had a very strong sense of smell.

Tanjiro: I can't tell you how many times my sense of smell has saved my life. In any case, I have this feeling that I shouldn't sever this rope with my sword.

He then notices the rope around him and Izuku.

Izuku: Oh, this? You see, my plan was that if I tied a rope to both of our wrists, at least one of the vestiges could enter your dream and inform you on what to do.

Tanjiro: Well it worked. Hikage Shinomori was there.

Izuku: Ok, I have a plan. Nezuko?

Nezuko: What is it, Izu?

Izuku: We need to burn the other ropes so that the others can wake up.

Nezuko: On it!

Nezuko started out with Zenitsu. Then Inosuke. Then Katsuki.

Tanjiro: Zenitsu, wake up!

Izuku: Kacchan! Snap out of it!

Tanjiro: Can you hear me? You've gotta wake up, Zenitsu!

Izuku: Stop being so difficult!

He would not wake up. Instead, he would snore.

Izuku: Man, this is more annoying than that time we were getting haircuts!

[There should be a GIF or video here. Update the app now to see it.]

(End of Flashback)

Tanjiro: Inosuke, wake up, please! It's no good, Izuku. They won't wake up. What do we do?

He turns to see that the girl that Rengoku was choking broke free but was tied up by Blackwhip.

Girl 1: You're all interfering! Now that you people are here, we won't get any happy dreams!

The others wake up and are getting ready to fight, but are tied up by Blackwhip as well. The girl turns to the boy that was in Tanjiro's dream.

Girl 1: Get off your ass, and come help us out! I don't care if you have tuberculosis. If you don't do your job, I'll go tell him, and then he won't show you any more dreams!

The boy gets up.

Tanjiro: 'Was he connected to my dream?'

The girl that was in Izuku's subconscious gets up too.

Girl 2: How are we so sure that Enmu will keep his word?

Izuku: Enmu?

Izuku turns to the crying boy.

Izuku: And you have...tuberculosis? I'm so sorry. However...I...we may have to fight back. I don't want that. But if I have no choice...I will do so.

Izuku rushes to the captured kids and knocks them out.

Tanjiro: So they just wanted happy dreams, didn't they?

Izuku: That's what the girl over there told me.

Tanjiro: I wanted that as well. I wish this was just a bad dream.

Izuku: What do you mean?

He turns to see Nezuko crying as she hugs him.

Nezuko: Our family was murdered by Kibutsuji. On the same day I was turned into a demon. My mother, Kie. My younger brother, Takeo. My younger sister, Hanako. My other younger brother, Shigeru. And my youngest brother, Rokuta. They were all murdered by him.

Izuku: What about your father?

Nezuko: He died from an illness long before then. On top of all that, Kibutsuji turned me into a demon.

Izuku: ...I know what it's like to lose someone.

Nezuko: What do you mean?

Izuku: You see, I wasn't the first choice to become the ninth wielder of One For All. There was this man who was just as big of a fan of my idol as I was. He had a student known as Mirio Togata. HE was the first choice. The name of that man was Sir Nighteye. I chose to do my work studies with him to get a better understanding of my quirk. However, one day while we were out patrolling, a little girl bumped into me. That little girl was Eri. We managed to find out that she was being tortured by the Yakuza. So me, Mirio, Sir Nighteye, and a bunch of my other friends raided the Yakuza to rescue Eri. We managed to succeed...but one of us didn't make it out alive. That was Sir Nighteye. He was impaled by a spike and died as a result. I felt horrible about it all. But there is something I will never forget about him. He once said: "Without joy and laughter to balance the sorrow, this world can never hope to have a bright future." I still remember those words. And I think you both should do the same.

Tanjiro and Nezuko were in awe at what he said. They knew he was right.

Boy: 'Until I experienced the warmth of his soul, I was willing to hurt others if it ment I could escape from the pain of my own illness. But now...'

Tanjiro and Izuku: Are you alright?

Boy: I am now. *sniff* be careful.

The other three smile.

Izuku and the Kamados: Thanks.

Izuku: And please...don't forget what I just said. *Turns to Tanjiro and Nezuko* All right. Let's go.
The three rush off. Eventually, Tanjiro stops.

Izuku: Tanjiro? What's wrong?

Tanjiro: It's the demon. His scent is overwhelming, even in such a strong wind. How did I manage to sleep through it? Even if each car was closed off and airtight, it's unbelievable.

Izuku: Whatever the case, we still have to stop the demon. Where is he?

Tanjiro: The demon's upwind. Maybe in the first car? We'll need to get on top.

Nezuko: That won't be easy.

Izuku: For most people. But luckily, I am here.
Izuku proceeds to use Blackwhip on the train car's roof from the outside and pulls himself up.

Izuku: All right! I'll bring you guys up!

Nezuko: No! Just bring Tanjiro up! There might still be other demons on the train and I need to protect the others while they're still asleep!

Tanjiro: Are you sure, Nezuko?

Nezuko nods with a determined look in her eye.

Tanjiro: I understand. You heard her, Izuku! Just me!

Izuku: On it!

Izuku proceeds to bring Tanjiro up with Blackwhip. They then run to the front of the train. But they encounter...

Nana: Hey, Ninth! I think this might be that Enmu guy the little girl you knocked out was talking about!

Kudo: Doesn't look like much to me.

En: Maybe so, but the fact is, he's still a demon. Don't let your guard down, Ninth!

Izuku nods.

Enmu turns to see the two demon slayers.

Enmu: What's this? You're awake now? Good morning.

Daigoro: He does know it's the middle of the night, right?

The other vestiges just look at him with a deadpan expression.

Enmu: What a shame.

He shows the back of his hand...WHICH HAS A MOUTH!

Nana: EW! THAT IS DISGUSTING!

Enmu: You could have stayed dreaming forever.

Tanjiro: 'He's the one.'

Izuku: 'Danger Sense is going crazy. But what's that in his eye?'

Enmu: Why are you two awake? Did I not show you dreams tailored to your every desire?

Izuku: 'Is that what the others are dreaming about? I'm willing to bet Kacchan's dream has him easily defeating a powerful opponent. But that's not important.'

Enmu: If I had so wished it, it could have been a dream where your family was being slaughtered. Would you have liked that one better?

He was looking at Tanjiro when he said that. He then turned to Izuku.

Enmu: And as for you. What was wrong with the dream I had shown you? I thought you would have loved being respected as the hero of the entire planet.

Izuku: 'So that's what my dream was supposed to be?'

Enmu: Would you have preferred a dream of you wanting to commit suicide again?

Tanjiro: 'That's right. I remember!'

(Flashback)

Gyomei: Alas, to see such a pitiful creature as this. I grieve for him. And I suppose the green one too. Perhaps it would have been better if they hadn't been born.

Izuku: I try to avoid thinking those thoughts again. I've thought about suicide way too much.

(End of Flashback)

Tanjiro: 'I'll have to ask him another time.'

Enmu: Of course not. Much too distressing. Or here's an idea. *Looks at Tanjiro* A dream where YOUR dear father comes back to life. *Turns to Izuku* And a dream where YOUR dear father returns from overseas.

Tanjiro was getting angry.

Izuku: Tanjiro. Calm down. He's trying to provoke us.

Izuku turns to Enmu.

Izuku: Let me guess. You enjoy showing people happy dreams before dragging them down into the worst nightmare of their lives. You enjoy seeing the look of confusion and horror on a human's face. Almost like a sadist. You want to watch as their spirit and will to live completely disappears. Your methods may be roundabout, but you certainly aren't distracted. You mixed your blood with the ink on the tickets we purchased, and once the conductor punched holes in them, your BDA is triggered and we all fall asleep. You did this all while at a safe distance. It took more effort, but you managed to succeed in putting us to sleep. You had to do this without being detected, otherwise the illusion that held us inside our dreams would stop and we would wake up. Am I correct?

Enmu's eyes widened in shock. A mere human was able to piece together so much about him. And they met only about a minute or two ago. It honestly impressed him.

Izuku: I can tell by the look on your face that I'm right.

Enmu: You certainly are. 'I can see how he managed to wake himself up. But why did the one with the red hair manage to wake himself up? Perhaps it was thanks to the green haired boy. He's smart. If he were a demon, I have no doubt he would be able to ascend to the Lower Moons. Maybe even the Upper Moons. Still, though, when the human desire to wrap themselves in a cheerful world of their own imagination...' is of such a giant magnitude?

Tanjiro and Izuku unsheathe their swords.

Tanjiro: Intruding on one's soul is something I won't allow!

Izuku: 'Full Cowling: 30%!' This trespassing of yours...

Both: Shall not stand!

Enmu then notices Tanjiro's hanafuda earrings.

Enmu: 'What's this? Those earrings he's wearing...'

He then smiles.

Enmu: What good fortune! Like a moth to flame, he came right to me!

Izuku: 'What is he talking about? And does he mean me or Tanjiro?'

Enmu: Could this be a dream? Now I can receive an even greater share of Master Muzan's blood!

Izuku: 'Muzan?! Perhaps more information can be gathered by him. But what do either of us have to do with him? Why does Muzan want me or Tanjiro dead specifically?'

Enmu: Once I've done so and become even more powerful, I can challenge an Upper Rank demon in a duel and usurp their place!

Izuku: 'Upper Rank? What does he mean by that? No. There's no time to think about that. I can ask Tanjiro later. We have to fight.'

The two take up a fighting stance.

Tanjiro: Water Breathing. Tenth Form... Constant Flux!

Enmu: Blood Demon Art!

Tanjiro rushes at Enmu.

Izuku: Tanjiro! Wait!

But it was too late.

Enmu: Whispers of Ordained Unconscious Mesmerism. Go to sleep dear child.

He unleashes a wave from his hand...mouth...thing and puts Tanjiro to sleep. Luckily, he woke up before he could even hit the ground.

Izuku saw this as an opportunity to rush in.

Enmu: 'It didn't work?'

Izuku: Moon Breathing. Third Form... Loathsome Moon, Chains!

Izuku unleashes two crescent slashes and manages to scrape Enmu's legs. Unfortunately, that was only because he narrowly dodged the attack that was aimed for his neck.

Enmu: 'He knows Moon Breathing? How? I thought only Upper Moon 1 knows it. Maybe I should ask Master Muzan later.'

While he was thinking, the two rushed at Enmu.

Enmu: Sleep now.

He puts them both to sleep. They were about to fall off the train, but they woke up before then and rushed at Enmu again. Enmu then pulls the same trick again. But despite that, they wouldn't stay asleep. So he tried again. And was met with the same result.

Izuku: 'It looks like he's able to use his BDA in rapid succession. Good to know. But it's useless if he can't keep us asleep.'

Enmu tries again but this time, they don't even slow down.

Enmu: 'Why aren't they affected? No... they are. They fall under the spell over and over.'

Enmu dodges their attacks multiple times and puts them to sleep.

Enmu: 'But each time they do, they stay self-aware and take their own lives in order to reawaken.'

They wake up and continue to try and decapitate him. But he keeps dodging.

Enmu: 'To commit suicide, even in the middle of a dream, to take their own lives with their own hands, means they have incredible willpower. Those two...are out of their minds!'

He puts them to sleep again...but doing so made him cause a fatal mistake. He showed Tanjiro his family, hating him for