(A/N): I love Demon Slayer and I actually just randomly had the idea for this pop into my head a couple of days ago so I hope you all enjoy it. Side note in this story all of the characters are older so keep that in mind and I am not necessarily following the traditional timeline. I think this story is different from the others in this book, so if you like it let me know
------------------------------------------------------------------------------------------------------------------
(Y/N)'s POV
I was sitting on a bench next to a ramen cart enjoying a bowl of curry chicken ramen. When I finished I noticed my crow flying above me before landing on my arm.
Crow: Head north. Head north into the mountains where families are turning up dead.
He started flying ahead of me so I could follow him as I ran close behind. By the time I reached the base of the mountain the sun was already setting.
(Y/N): I need to hurry. I don't want to give the demon too much time to hunt.
I said as I continued running, but the air was much thinner making it hard to breathe properly. Trying to find the demon was going to be difficult seeing as there are so few houses and they are spaced so far apart. I finally located a house, but all seemed normal and everyone appeared to be safe.
???: AAAAAHH!!!
The scream came from the woods behind the house.
(Y/N): That must mean the demon is close.
I took off in that direction until I spotted a demon in front of a storage shed holding a girl by the throat.
They both noticed me.
Demon: Another human to feast on aren't I lucky.
Girl: Please help me.
She said weakly as the demon still had a firm grip on her throat.
Demon: Quiet you.
(Y/N): Don't worry ma'am I won't let this demon harm you.
I said as I pulled out my red Nichirin sword.
Demon: Do really think a pathetic brat like you could...
Before he could finish his sentence I had sliced through his arm that was holding the girl.
Demon: Ah! Darn you, you'll pay for this!
He yelled as I was facing the girl.
(Y/N): You're safe, just stay behind me while I finish this.
As I turned around the demon was too close and I couldn't get out of the way fast enough so his claw-like fingers cut deep into my chest. Before he could get another hit in, I kicked him away.
Demon: See I knew you were weak. Once I kill you I will devour that girl and everyone else on this mountain.
Instead of responding, I took a deep breath.
(Y/N): Total Concentration. Flame Breathing First Form Unknowing Fire.
My sword lit up with fire as I quickly charged at him and slashed at his neck. In that one quick movement, I decapitated him and watched his head when flying. After his body disintegrated I turned to see the woman on the ground still in shock. I walked over to her.
(Y/N): It's ok the demon can't hurt you anymore. Let's get you back home.
I said, offering her my hand. She put her hand in mine and I helped her to her feet.
Girl: Thank you.
(Y/N): You're welcome. Just be sure not to go out after dark. It isn't safe.
I walked the girl home and once she was instead I took a moment to rest because my chest was really killing me. I opened my shirt to see the bleeding hadn't stopped so I took some spare cloth and tied it around my chest to compress the wound until I could get help.
(Y/N): The Butterfly Mansion isn't too far. If I hurry I can make it there by morning.
With that, I decided to make my way to the Butterfly Mansion. It was a long walk. By the time I arrived the sun had been up for at least three hours. I didn't see anyone outside so I entered and walked in the direction of the medical wing. As I turned a corner I almost bumped into someone.
(Y/N): Oh hi Nezuko, I'm sorry I didn't see you there.
She removed the bamboo from her mouth.
Nezuko: Welcome back (y/n).
(Y/N): Thank you. It's good seeing you out and about during the day.
I'll be honest I still haven't gotten used to seeing Nezuko during the day yet even though it's almost six months. She also had gotten much better at talking.
(Y/N): I guess this must mean that Tanjiro and the others are here as well.
She nodded.
(Y/N): Have you seen Aoi?
She pointed to one of the medical rooms down the hall.
(Y/N): Thanks.
I said as I was about to walk past her, but she reached for my hand and put it on her head. I figured she wanted me to give her head pats so I did. She was very happy about it as she looked at me with sparkling pink eyes.
(Y/N): I'll see you later.
She huffed as I left her in the hallway. I went to the medical room to find Aoi treating some other injured demon slayers.
Aoi: (y/n) I didn't know you were here.
(Y/N): I just got here sorry for letting myself in. I just need to be bandaged up a little.
Aoi: Take the bed over there and I will get to you soon.
I did as she said and got in the bed. Shortly after Aoi came back with supplies to clean and bandage the wounds.
Aoi: Take off your shirt.
I took off my shirt and the cloth I used to compress the wounds which were covered in dried blood.
Aoi: These cuts are pretty deep. You will need to stay here for a week before lady Shinobu determines whether or not you can return to duty. Why don't you go get washed up then we will take care of this.
(Y/N): A week?
Aoi: At least, but I'm sure you can find a good way to spend your time. I know for a fact that Sumi will be very happy to see you.
I smiled at her comment then went to take a bath. Once I was done getting taken care of I didn't really feel like lying down so I ended up going outside to enjoy the garden. When I got outside I saw three girls have a conversation.
(Sumi is on the left, Naho is in the middle, and Kiyo is on the right)
All Three: (Y/N)!
Sumi: I am so happy to see you. What are you doing back?
(Y/N): Well you know.
Sumi: Are you hurt?
(Y/N): Nothing serious.
She was giving me a concerned look.
(Y/N): I promise I'm fine.
We smiled at each other.
Naho: Oh Kiyo don't we have to go do that thing.
Kiyo: Yeah we have a thing to do. We will leave you guys alone.
Naho: We can catch up altogether later (y/n).
They went inside leaving us alone. Sumi jumped into me wrapping her arms around my neck. I held her tightly so she wouldn't fall.
Sumi: I missed you so much.
(Y/N): I missed you too.
I gave her a kiss and she returned the favor tenfold by kissing me over and over again.
Sumi: I've been so worried about you. Were you hurt badly?
(Y/N): Nothing serious, just some cuts to the chest.
I opened my shirt just a little so she could see the bandages, but her worried look returned.
(Y/N): Don't worry it's already healing plus this buys us a week together.
Sumi: We can have a lot of fun over the course of a week.
(Y/N): Yes we can.
We moved in to kiss each other again, but we were interrupted.
Tanjiro: Hey (y/n). How have you been?
I saw Tanjiro waving at us with Kanao, Zenitsu, and Inosuke standing with him. Sumi and I moved apart from each other because we were keeping our relationship a secret.
They came over to us.
Insouke: (y/n)! You're strong, I demand you fight me now.
Zenitsu: Cut it out. Why do you wanna fight everyone?
Insouke: Don't tell me what to do.
Tanjiro: Hi Sumi didn't see you there. We were on our way to visit the new sweet shop in the nearby village. Would you two like to join us?
(Y/N): I can go.
Tanjiro: Sumi?
Sumi: I can go too.
Tanjiro: We should see if Nezuko wants to come with us.
Right after he said that Nezuko came out into the garden.
Zenitsu: Hi Nezuko.
He said in an ogling tone as he went up to her like a love-sick puppy.
Zenitsu: Did you come out here to see me?
He continued on a ramble about how much he loved her, but she didn't seem to care. She looked at me smiling then came over to me.
Tanjiro: Nezuko must like you (y/n).
She nodded.
(Y/N): I like you too Nezuko.
I said as I gave her head pats. Of course, when I said I liked her I meant as a friend.
Zenitsu: WHAT!?!?!?!?!? I'll KILL YOU FOR STEALING MY NEZUKO!
He drew his sword. Sumi hid behind me, but Nezuko stood in front of me. Before he could do anything Kanao got him to the ground.
Tanjiro: Calm down Zenitsu.
It took a minute, but Tanjiro was able to calm him down. We proceed with our plan and as we walked Nezuko grabbed my hand and wouldn't let go so I just let her hold my hand for the duration of the walk. While we were at the shop we tried some great desserts then decided that while we were out we should get dinner. We found a nice noodle restaurant and sat down. Tanjiro, Kanao, Inosuke sat across from me with Sumi on one side and Nezuko on the other with Zenitsu was next to her.
3rd Person POV
Tanjiro: It's so good when we can take a quick break from the constant fighting and spend time with the people we care about.
He looked at Kanao who blushed deeply. Zenitsu stared at Nezuko with heart-shaped eyes. (y/n) and Sumi locked eyes. Nezuko was glaring at Sumi because she saw her smiling and taking long looks at (y/n).
Inosuke: I don't get this lovely Dovey stuff. It makes you weak.
(Y/N): Oh please, you totally have feelings for Aoi.
Inosuke: That's not true.
Zenitsu: I think I can see you blushing under your boar head.
Tanjiro: If you like Aoi you should tell her how you feel, don't you agree Kanao?
Kanao: Yes.
The group continued to talk and have a lovely meal. Once they finished their meal they were getting to return to the butterfly mansion, but someone seemed a little too tired to walk.
Tanjiro: What's the matter Nezuko?
She took the bamboo out of her mouth.
Nezuko: I'm tired.
Tanjiro: We'll be at the mansion soon so you can rest then. If you want I can carry you back.
Zenitsu: I can carry you back, Nezuko.
Nezuko: No. (y/n).
She ran to (y/n) jumping into his arms, surprising him. He was now holding her bridal style.
Tanjiro: Sorry (y/n) she normally doesn't act like this.
Zenitsu: My arms were open for you.
(Y/N): It's ok, I don't mind carrying her.
Tanjiro: You sure?
(Y/N): Yeah. Plus Zenitsu you have nothing to worry about because I actually am in love with Sumi.
Sumi: You said you love me? I love you too.
Kanao: Sumi, I am happy for you, but I know.
They continued talking about (y/n) and Sumi's relationship as they walked back. Everyone was too distracted to notice how upset Nezuko seemed to be. At the mansion, she watched as (y/n) and Sumi went into the same room together. Once they were in the room they closed the door and got ready for bed.
Sumi: I am very happy that you said you love me, but why did you make the sudden decision to say that.
(Y/N): I don't think I could listen to Zenitsu winning anymore and I didn't want to make you feel jealous.
Sumi: I wasn't really jealous.
(Y/N): I can fix that.
Sumi: Are you going to make me feel like the only girl in the world?
(Y/N): You can count on it.
He said as they started stripping off their clothes.
*Timeskip*
After having sex Sumi was lying her head on (y/n)'s chest trying to catch her breath. (y/n) was already asleep and as much as Sumi wanted to stay she didn't want lady Shinobu to accidentally find out like this. She kissed (y/n) on the cheek and left the room hoping nobody hurt her. Little did she know someone did hear her and was out in the hallway. They watched as Sumi left to return to her room and once she was out of earshot they entered the room to find (y/n) asleep. They kneeled down next to him and played with his hair. Then she kissed him on the lips.
(Y/N): Sumi, I thought you went back to your room.
He said while still asleep. The person got up and left the room.
*Timeskip*
(Y/N)'s POV
???: AAAAAHHHH!!!!!
I woke up to the sound of a blood-curdling scream. I threw on some clothes and grabbed my sword. I heard the commotion and yelling coming from the east wing of the mansion. Demons must have found Demon Slayer HQ and were attacking. When I arrived at the scene I was horrified. The bodies of the demon slayers staying in the medical ward on the ground are torn apart. There was no time to feel sick because I saw someone flying into the wall, it was lady shinobu.
(Y/N): Lady Shinobu, are you ok? What's happening?
Shinobu: It's Nezuko.
She said in a weak voice before she passed out. I couldn't believe it. It can't be Nezuko; she'd never hurt a human. I heard footsteps and saw the demon enter the hallway.
This couldn't be the sweet Nezuko from earlier. I noticed she had something in her hand. It was one of Sumi's butterfly hair clips covered in blood.
Nezuko: (y/n).
(Y/N): Sumi!
Nezuko: She's gone.
Those words broke my heart. I could feel tears streaming down my face.
(Y/N): Total Concentration. Flame Breathing Fifth Form Flame Tiger.
Fire shot out of the sword as I released powerful slashes at her. I wasn't able to get her neck, but I cut off her arm and leg. She instantly regenerated those body parts and kicked me through the wall. I saw the others arrive and rush to my aid.
Tanjiro: Are you ok?
(Y/N): She definitely broke my ribs.
Zenitsu: Who?
(Y/N): It's Nezuko.
She entered the room in her demon form.
Tanjiro: Nezuko, why are you doing this?
Nezuko: I love (y/n).
(Y/N): She killed Sumi and others.
Kanao: We must kill her before she hurts others.
Inosuke: I'll stop her.
He rushed at her.
Zenitsu: Don't she's too strong.
Inosuke: Total Concentration. Beast Breathing Third Form...
She grabbed him by the throat crushing his windpipe preventing him from using total concentration breathing. She slammed him to the ground.
Tanjiro: Inosuke!
Kanao: We should all attack her together?
(Y/N): Total Concentration. Flame Breathing Ninth Form Rengoku.
Zenitsu: Total Concentration. Thunder Breathing First Form Thunderclap and Flash.
Kanao: Total Concentration. Flower Breathing Fifth Form Peonies of Futility.
Tanjiro: Total Concentration. Hinokamki Kagura Dragon Sun Halo Head Dance.
We all launched our attacks at Nezuko. The impact from all the attacks landing at the same time destroyed the remains of the east wing and sent us all flying in different directions. I was sure we got her with that. I looked around to see the true destruction, but a dust cloud had made it hard to see anything.
(Y/N): Tanjiro, Kanao, Inosuke, Zenitsu, Lady Shinobu!
I called out to them.
Tanjiro: (y/n) I'm ok. I can't find the others.
(Y/N): We need to make sure Nezuko is down first.
I started moving around the dust cloud trying to find Nezuko's body before it disintegrates to make sure she is dead. I saw a figure standing there, but it didn't look right. When I got close I could see it was Nezuko with all of her limbs including her head were detached, but it was still attached because she salitafied her blood to keep herself from dying.
(Y/N): No!
If that didn't work, what are we supposed to do because she can't die from sunlight. I guess we need to hold out until other Harisha get here. She reformed and didn't have a scratch on her.
Nezuko: Stop fighting (y/n). I love you and I would hate to have to break all the bones in your body, but I will. If you come with me I will let everyone else go unharmed.
She stretched her hand to me with a smile.
Nezuko: Don't be stupid my love. Your future is with me forever.
I was still incredibly upset and angry about Sumi. I would never forgive her for taking her away from me, but there is already so much carnage.
Zenitsu: Total Concentration. Thunder Breathing First Form Thunderclap and Flash GodSpeed.
He launched at Nezuko, but even with God Speed he missed. Nezuko grabbed his leg and ripped it off. She grabbed him by the shirt.
Zenitsu: I love you Nezuko, please don't do this.
Nezuko: Get this through your head. I never loved you. (y/n) is the only one for me.
She ripped his head off and tossed it away. She had to die. I grabbed my sword and charged at her, but I stumbled. I looked to see I was bleeding heavily and one of my legs was broken. With all the adrenaline rushing through my body I didn't feel it happen. Nezuko walked over to me.
Nezuko: You're mine now.
I started crawling away from her, but she stepped on my back hard.
Nezuko: I'm not gonna let you die. In fact I might turn you into a demon so we can be together till the end of time.
(Y/N): Never.
She kicked me in the head, knocking me out.
3rd Person POV
Nezuko picked up (y/n) in her arms and was about to leave, but she saw Tanjiro and Kanao getting back up.
Nezuko: I'm not going to kill you Tanjiro so don't try to follow me.
She took off and they decided not to follow instead they went to treat the wounded. By the time the other Harisha arrived they decided that they would let Tanjiro live if he spent his life tracking down his sister because a murderous demon that can't be killed my sunlight is to dangerous to be left alive. Elsewhere Nezuko had (y/n) chained up and was still debating on whether or not to turn him into a demon, but while she was still deciding she was having sex with him every opportunity she got in order to make him love her or produce a child. After finishing another round of sex Nezuko forced (y/n) to look at her.
Nezuko: I made up my mind that you are going to become a demon. That way I can keep you locked up forever if you don't accept my love. I'll let you rest for now darling because the process is going to be extremely painful. I'll make it up to you after with my endless love and affection. I love you.
------------------------------------------------------------------------------------------------------------------
Let me know what you think of this chapter. If you enjoy it, be sure to like and comment on something good.