A young adult male, Tanjirō, carries his sister, Nezuko, on his back through the snow. Nezuko is bleeding from a wound on her head. His family and two strangers are following.
Tanjirō: How...? How did this happen? "Nezuko, don't die! Don't die on us! I'm gonna save you no matter what! I won't let you die! I swear your big brother will save you no matter what!"
~At a small cabin in the mountains, during the morning~
Tanjirō takes up a basket of charcoal on his back and is preparing to leave the house.
Kie: "Tanjirō? Your face is covered in soot. Come over here."
Kie comes out of the house and wipes Tanjirō's face with a towel.
Kie: "It's dangerous with all this snow. You don't have to go, you know."
Tanjirō: "Well, I want everyone to eat their fill on New Year's, so I'm gonna sell as much charcoal as I can."
Kie: "Thank you."
Shigeru: "Big Bro!"
Tanjirō: "Hmm?"
Tanjirō's younger brother and sister, Shigeru and Hanako, come running to Tanjirō. Another brother, Takeo comes out from behind them.
Shigeru: "You're going to town again today?"
Hanako: "I'm going with you!"
Kie: "Oh no, you're not. You know you can't walk fast like Tanjirō."
Shigeru: "Mom!"
Kie: "You may not. Since he can't use the cart today, he won't be able to give you a ride when you're tired."
Shigeru: "Big Bro!"
Shigeru runs to Tanjirō and clings onto him.
Hanako: "I wanna go with you! I promise I'll help you!"
Tanjirō pats Hanako's head.
Tanjirō: "Thanks, Hanako. But you're staying home today."
Hanako: "What~?"
Tanjirō: "You too, Shigeru. But I'll get you tons of goodies, okay?"
Shigeru: "Really?"
Tanjirō: "Yeah. And Hanako, I'll read for you when I'm back."
Hanako: "Yeah!"
Tanjirō: "That's a good girl."
Kie: "Thank you so much, Tanjirō."
Tanjirō: "Sure. Okay, I'll be heading out now. Takeo, will you chop as much wood as you can?"
Takeo: "Sure, I'll do it, but... I was hoping we could do it together."
Tanjirō walks over to Takeo and pats his head.
Tanjirō: "There, there."
Takeo jumps away from Tanjirō's hand.
Takeo: "What's with that all of a sudden?"
Shigeru: "You're blushing, Take!"
Takeo: "Hey, you shut up!"
Tanjirō: "There, there."
Tanjirō continues patting Takeo's head, and Takeo jumps away again.
Takeo: "I said cut it out!"
All of the family laughs, and Tanjirō sets out for town with his three siblings and Kie watching him.
Shigeru: "Hurry back, okay?"
Hanako: "Be safe, okay?"
As Tanjirō walks off, Nezuko appears, carrying their youngest brother, Rokuta, on her back.
Nezuko: "Big Brother!"
Tanjirō: "Hey, Nezuko."
Nezuko: "I was putting Rokuta down for a nap, or he'd make a scene when you leave. He misses Dad a lot since he passed away."
Tanjirō pats Rokuta's head lightly.
Nezuko: "And everyone follows you wherever you go. See you later."
Tanjirō continues making his way toward town.
Tanjirō: We don't have an easy life, but we're happy. But life could change suddenly like the weather. It shifts and moves on. It's not like it always stays sunny, and it's not like it ever snows endlessly. And... whenever happiness is destroyed, there's always... the smell of blood.
~In the forest~
A portal opens and an owl demon walks through before turning and waiting for the angel to go through.
Uriel: "Is that how it feels to go through a portal?"
Y/n looks at him before a flash of blue appears in the corner of Uriel's eye.
Uriel: "Hmm? Y/n?!"
Y/n is now a tall, white-haired, pinked eyed female. Uriel looks at her and stares at her eyes which house child-like wonder in them.
Uriel: She's fairly pretty. Her long white hair is tied up into pigtails, she has soft pink eyes that seem so gentle, and she also has a larger-than-average bust, and a slim figure. I should probably get her something that covers her more, after all this is Japan and it's in the 1920s she'll get a lot of dirty looks for it. Her choker is pretty as well not what I was expecting. Her multi-colored bracelets make her hat look pretty too.
Y/n: "Take a picture it'll last longer, darling~"
Uriel: "I-I-I..."
Y/n: "It's fine I'm merely joking. I know you're not intrested. Let's get your human disguise."
A blue light covers Uriel.
Uriel: "What is this?"
When the light disappeared Y/n conjured a mirror for him to look at.
Uriel: "Hmm. I like it."
Y/n: "Good because there's no trades or changes."
~In town during the morning~
Tanjirō has made it down the mountain. He speaks to townsfolk down the street.
Woman 1: "Well now, Tanjirō! I can't believe you came down from the mountain on a day like this. You're such a hard worker! You might catch a cold, you know?"
Tanjirō: "This is nothing, really. Do you have enough charcoal?"
Man 1: "Hey, Tanjirō!"
Tanjirō: "Hmm?"
Man 1: "Can I have some charcoal?"
Man 2: "Thanks for fixing my sliding doors the other day."
Woman 2: "I'll need some charcoal, too!"
A door opens behind Tanjirō, revealing a woman holding a boy by the scruff of his clothes. The boy has blood coming from his mouth.
Boy: "Ah, Tanjirō! Oh man, perfect timing!"
The boy runs over to Tanjirō. He kneels and shows a bundle to Tanjirō.
Boy: "I've been accused of breaking this plate! Help me out, will you? Sniff it!"
Tanjirō leans down toward the bundle holding the shattered dish and sniffs it.
Tanjirō: "I smell a cat."
Boy: "You see?!"
Woman 3: "Oh my, so it was a cat?"
Boy: "I told you it wasn't me!"
Man 3: "Tanjirō! Can you give me a hand with this luggage?"
~At night~
Tanjirō is making his way back up the mountain.
Tanjirō: "Jeez, it's late already. I'm glad they're sold out, though."
Saburou: "Hey, Tanjirō!"
Tanjirō: "Hmm?"
Tanjirō turns around toward Saburou in his house at the base of the mountain.
Saburou: "Are you gonna go back to the mountain? You'd better not. It's too dangerous."
Tanjirō: "I've got a great sense of smell, so I'll be fine."
Saburou: "I'll put you up for the night. Come on. Get back here."
Tanjirō: "But..."
Saburou: "Don't argue! Come on! Before the demons show up."
~On the mountian~
Uriel: "Pardon me, madam. Would it be possible for us to spend the night? We are travelers and unfamiliar with the mountain's paths."
Kie: "Of course, and you must be freezing. What are you doing dressed like that?! Common let's get you into something warmer."
Y/n: "Thank you. Where I'm from it's common to dress like this because it gets in the triple digits often."
Y/n bows and pulls Uriel with her.
~In Saburou's house~
Tanjirō is given a meal and finishes it.
Tanjirō: "Thanks for the meal! Hey, Old Man Saburo, what are demons like?"
Saburou: "Man-eating demons have always prowled the land once it gets dark. That's why you should never stroll around at night. If you're done eating, go to bed. You can set off for home at first light."
Tanjirō lays down for bed.
Tanjirō: "These demons wouldn't come inside your house, would they?"
Saburou: "Yes, they'd come in."
Tanjirō: "Then, everyone would get eaten up by the demons."
Saburou: "That's why the demon hunters protect us by slaying them since way back when. Lights out now. Go to sleep."
Saburou turns out to lights.
Tanjirō: Old Man Saburo is all alone after losing his whole family, so he must be lonely. I'll bring my brothers and sisters next time and say, "You don't have to be scared. There are no demons. You're safe." But, come to think of it, my grandma used to say the same thing when she was alive.
~Meanwhile~
Y/n: "Uriel, do you smell it?"
Kie: "Smell what?"
Uriel: "Yes."
Y/n pulls out two of the angelic knives she was given as she prepares for the attack.
Y/n: "Take Kie and the kids upstairs, I'll stall him until you get back with the ropes."
Uriel takes up Rokuta and Hanako as Y/n pushes Kie, Nezuko, Shigueru, and Takeo back as a male burst through the door swinging two whips. Y/n cuts them off easily shocking the male when they don't regenerate.
Kie: "Y/n!"
Uriel runs down ushering Shigeru and Takeo upstairs while glaring at the male. Y/n slices all the whips and deflects the attacks thrown toward her. Uriel grabs Nezuko and Kie and pulls them upstairs but Nezuko breaks free and tries to grab the older teen protecting them only to get hit in the process. Uriel rushes toward her and grabs her noting the slight change of smell to her. He takes both upstairs and patches Nezuko up as Y/n holds her own. Y/n dodges another attack. Y/n electrocutes the male as Uriel rushes back down.
Y/n: "Remember we mustn't kill this one. He's to be taken back to Hell alive."
Y/n utilized telekinesis to forcefully propel him outside. The man landed near a tree and quickly regained his footing. Kie looks out the window watching the two strangers fight the male demon for her and her kids' protection. It seems like this battle is going to continue all the way through the night and into the morning.
~The next morning~
Tanjirō is leaving for the mountain.
Saburou: "You be careful now."
Tanjirō: "Okay!" Whenever happiness is destroyed, there's always...
On his way home, Tanjirō sniffs the air.
Tanjirō: "The smell of blood!"
Tanjirō races up the mountain and arrives at his house. He stops in his tracks. On the ground in front of the door is a pool of blood.
Tanjirō: "Ahhh!!!"
Tanjirō rushes into the house and straight to the kitchen. Uriel is sitting there pouting as Y/n poked his bandaged arm.
Y/n: "I can't believe you broke your wrist."
Kie: "Y/n. Stop that, you're also injured."
Tanjirō: "What happened? What's going on?! What happened here?!"
Kie: "Calm down, Nezuko is still asleep."
Uriel: "Well she does still need to go to the doctor. So pack up so we can get going."
Tanjirō: "Huh?"
Kie: "We're moving to a new home. There was a demon last night."
Tanjirō: Huh?! What are these two strangers? They don't smell human!
Tanjirō runs down the mountain, carrying Nezuko on his back. Y/n easily keeps up while holding Takeo and Hanako. Uriel is right behind them carrying Shigeru and Rokuta and helping Kie keep up.
Tanjirō: Nezuko's still warm! If I can get her to a doctor, she might survive! How did this happen? I can't breathe! The air's so icy! My lungs hurt! Keep moving forward! Move your legs faster! We still have a long way to go before we reach town. Hurry! I won't let you die!
Nezuko's fingers twitch. Y/n's eyes narrowed as she quickly placed Hanako and Takeo on Uriel and rushed toward Nezuko.
Uriel: "Oh no."
Kie: "What's wrong?"
Uriel: "Nezuko is waking up. And it seems Y/n has noticed something off."
Tanjirō: I'm gonna save you no matter what! I swear your big brother will save you no matter what!
Nezuko awakens. Her eyes are completely white, and she begins growling.
Tanjirō: "Ah!"
Nezuko: "Uraaa!!"
Nezuko pulls on Tanjirō's shoulders, and the two go tumbling down a cliff. Y/n jumps after them as Uriel groans.
Ureal: "Quickly, we have to find a safe way down."
Tanjirō: Oh no! "Ahh!!"
Tanjirō lands on his back in the snow.
Tanjirō: I was saved by the snow. I slipped because of the snow to begin with. "Nezuko?"
Tanjirō looks around for Nezuko. She stands far from him, barefoot and head hung low.
Tanjirō: "Nezuko, are you alright? You don't have to walk! I'll carry you to town, okay?"
Tanjirō runs over to Nezuko.
Tanjirō: "Nezuko!"
Nezuko raises her head. Veins pop from her face, and her teeth are sharp. She lunges toward Tanjirō.
Nezuko: "Arhh!!"
Tanjirō: "Wah!"
Before Nezuko can bite him, Tanjirō takes the axe from his belt and puts the handle between Nezuko's teeth. They struggle, but Nezuko pushes Tanjirō down into the snow. Tanjirō continues to push Nezuko away with the axe handle.
Tanjirō: Sh-She's... a demon! I just remembered what Old Man Saburou told me. Nezuko's a man-eating demon? No! Nezuko's been a human ever since she was born! However, she no longer has Nezuko's scent. But it wasn't Nezuko's doing! She was lying asleep, and there was no blood on her mouth or hands. And there was one more... There was one more scent!
Nezuko's body trembles.
Y/n was watching the siblings.
Y/n: This demon girl has the potential to be different. It's best I don't interfere.
Tanjirō: "Sh-She just grew in size!" And she's getting stronger and stronger! While I was sleeping carelessly at Saburou's house, they were attacked brutally like that! I know it must've hurt! You suffered, didn't you? I'm so sorry I couldn't save you. If only I could help Nezuko at least... But she's too strong for me to push her back! "Nezuko! Hang in there, Nezuko! Don't give in! You gotta hang in there!"
Someone is running toward Tanjirō and Nezuko.
Tanjirō: "Don't turn into a demon! You gotta stay strong! Hang in there! Hang in there!"
Tears fall from Nezuko and drop onto Tanjirō's face. Tomioka reaches Tanjirō and Nezuko. He jumps into the air to attack Nezuko, but Nezuko realizes his presence. Before she can attack, Y/n pushes her and Tanjirō out of the way, causing Tomioka to cut off some of Tanjirō's hair. Tanjirō and Nezuko are blown back into a tree.
Tanjirō: What the... Who's that? A sword?
Tomioka: "Why are you protecting it?"
Tanjirō: "She's my sister! She's my younger sister!" Nezuko begins growling again and trying to get away from Tanjirō.
Tanjirō: "Nezuko!"
Nezuko: "Uaruhhh!"
Tomioka: "You call that thing your sister?"
Tomioka launches himself at Tanjirō and Nezuko, ready to strike. Tanjirō moves to protect Nezuko but realizes that she is no longer under him. When he looks up, Tomioka is holding her in the distance by the scruff of her clothes.
Tanjirō: "Nezuko!"
Tomioka: "Don't move."
Tanjirō: "Ah..."
Tomioka: "My job is to slay demons. Needless to say, I'm going to decapitate your sister."
Tanjirō: "Hold on! Nezuko hasn't killed anyone! Back at my house, there was another scent that I'd never smelled before! That's probably the one who attacked my family! It wasn't Nezuko! I don't know why she turned into something like that, but... but still...!"
Tomioka: "It's quite simple. Because her wounds were exposed to demon blood, she turned into a demon. That's how man-eating demons multiply."
Tanjirō: "Nezuko would never eat humans!"
Tomioka: "You gotta be kidding. Just now, you were about to be devoured."
Tanjirō: "You're wrong! I'm sure she knows who I am! I won't let her hurt anyone! I'm going to turn Nezuko back into a human! I swear I'll heal her!"
Tomioka: "She can't be healed. Once you become a demon, you can never go back to being human."
Tanjirō: "I'll find a way, no matter what! So, please... don't kill her! I'll hunt down the one who attacked my family!"
Uriel gets there with Kie and the other kids.
Kie: "Nezuko!"
Tomioka readies his sword to kill Nezuko.
Tanjirō: "I'll make everything alright! Please! Please!! Don't do it!"
Tanjirō gets on his knees and bows with his head to the ground.
Tanjirō: "I'm begging you not to... Please... don't kill my younger sister! Please don't do it. I'm begging you..."
Tomioka: "Grr... Don't ever give others a chance to murder you!"
Tanjirō: "Wha..."
Tomioka: "Stop that pathetic groveling! If it was the least bit effective, your family wouldn't be dead! Can a weakling who can't take the initiative in such a situation heal his sister?! Hunt down the enemy?! Don't make me laugh! The weak have no rights or choices! Their only fate is to be relentlessly crushed by the strong! The demons might know how to cure your sister! But don't think that a demon would respect your will or wishes! Naturally, I have no respect for you, either! That's reality! Why did you throw yourself over your sister earlier? Was that your way of protecting her? Why didn't you swing your hatchet? Why did you show your back to me? All those blunders led to your sister's capture! I could have skewered her along with you!"
Y/n's eyes glow slightly catching Uriel's attention.
Giyu: Don't cry. Don't despair. Now's not the time for that. I know you're devastated. Your family was almost massacred, and your sister's become a demon. I know it's painful. I know you want to scream. I get it. If only I'd gotten here a half-day sooner, your family might not have ended up like this. But there's no way to turn back time. Feel the rage. The powerful, pure rage of not being able to forgive will become your answering drive to take action! With such a fragile resolve like yours, you can't protect your sister or heal her, or get revenge for your family!
Tomioka glares at Tanjirō and readies his sword again to kill Nezuko.
Tanjirō: "No!"
Uriel covers the scene from the kids.
Nezuko: "Arghhh! Ahhh!!"
Tomioka stabs Nezuko in the chest.
Tanjirō: "Stop!"
Tanjirō throws a rock at Tomioka, who bounces it off his sword. Tanjirō then gets up, grabs his hatchet, and runs through the trees, continuing to throw rocks at Tomioka. When he gets close enough, Tanjirō runs toward Tomioka to attack.
Tanjirō: "Arghhhh!!"
Tomioka: A straightforward attack driven solely by emotion... "You fool!"
Tomioka hits Tanjirō with the butt of his sword, knocking Tanjirō out cold. Nezuko stops struggling and stares at Tanjirō's body on the ground. Uriel lets the kids watch.
Tomioka: Hmm? Where's his hatchet?
Tanjirō's hatchet comes flying through the air from above, striking the tree behind Tomioka's head.
Tomioka: Just before he hid behind the tree, he hurled that rock toward me and, at the same time, tossed the hatchet in the air. He hid his hands as he pretended to attack so I wouldn't realize he was unarmed. He knew he couldn't beat me. He tried to bring me down after I struck him! This kid...
Nezuko: "Uaar!!"
Nezuko breaks free from Tomioka's grasp and kicks him away. She runs toward Tanjirō.
Tomioka: "Damn! She'll devour him!"
Kie goes to run toward them but is stopped.
Uriel: "Do not interfere with the test. Y/n is supervising and will step in when Nezuko is a danger or in danger."
Nezuko kneels in front of Tanjirō's unconscious body to shield him.
Tanjirō: (Flashback) Nezuko... It wasn't Nezuko! She'd never eat humans!
Nezuko: "Graahh!"
Nezuko lunges toward Tomioka. She begins attacking him. He dodges her attacks.
Hanako: "Big sis is protecting Big Bro!"
The family, Uriel, and Y/n watch.
Tomioka: Long ago, someone said the same thing, only to be devoured by a demon. When a demon is starving, it will kill and devour even its own parents or siblings because they're nutrient-rich. I've seen it happen more times than I can count. This girl has been wounded, and she's expending energy to heal those injuries. She must've drained vast amounts of her strength as she transformed into a demon. That means she's severely starved at this moment, without a doubt. She must've wanted to feast on a human right away, even if it was her own brother... Yet she protected him instead, and she even intimidated me...
Nezuko jumps to a tree and lunges at Tomioka again. He sheathes his sword.
Nezuko: "Grr!!"
Tomioka: I wonder... These siblings might be... different from others.
Tomioka strikes Nezuko on the side of her neck, knocking her out cold. Uriel lets Kie go as Y/n steps out of the shadows.
Kie: "Nezuko! Tanjirō!"
Kie rushes towards her eldest two, the kids following. Tanjirō is still face-down in the snow. He grabs onto the nearest thing he can. Nezuko is laid down next to him on her back. She has a bamboo gag in her mouth, attached by a length of fabric tied around her head.
Tanjirō: "Wha..."
Hanako: "You're awake!"
Tomioka: "You awake?"
Tanjirō: "Ah...!"
Tanjirō gets up and moves to protect Nezuko.
Tomioka: "Go see an old man named Sakonji Urokodaki who lives at the foot of Mt. Sagiri. Tell him that Giyuu Tomioka sent you. She seems to be alright since it's cloudy now, but never let her be exposed to the sunlight, okay?"
Tomioka disappears in a flash.
Y/n: "Ahhh."
Y/n looks at Kie.
Kie: "Let's get going."
Y/n: "Kamado-San, we apologize for the trouble we've put you through."
Kie: "It's fine, without you two we'd be dead."
Tanjirō: "Let's go."
The family and two beings walk down the mountain.