Y/N's POV:

“We need to go find Tanjiro” you tell Zenitsu as you grab his arm and led him back and out of the train. “Y-Y/N! If it is a uppermoon, wouldn't it have already eaten Kanao!?” Zenitsu cried in fear and sadness. You didn't respond, the grip of your hand on his wrist was enough to tell him to stop talking. Your mind was filled with thoughts about what you should do next and what to tell Tanjiro. You knew Tanjiro and Kanao had some sort of feeling for one another, and having to tell Tanjiro that Kanao might be dead made you want to throw up in disgust. You found the town where Tanjiro and the rest went to awhile ago and walked towards it. It was quite small... Some houses, some a little run down or had peeled off paint. There was a few fenced off areas with animals inside, but there was very little people, so finding Tanjiro and the others were quite easy. Tanjiro wasn't acting like himself either. He was probably still upset about Kanao, so you chose to not talk about your findings until he was thinking properly.

Tanjiro and Inosuke were in an inn when you and Zenitsu found them. “We're staying here for the night?” Zenitsu asked at last. “Yea... We need to all rest after that fight” Tanjiro answered. You nodded your head and followed after Inosuke who rushed up the stairs. The room was quite small but all 4 of you and Nezuko's box could fit and sleep for the night. “I'll be out” you say as you exit the room immediately after, not waiting for a response. You exit the building to the now early morning of the sky. You wanted to see what the town had. Most of the stalls were closed with only a few stuff that were being sold. You scan the area and found a closed stall with a few old stuff on a bench, one of them being an old journal. You pick it up and scan through the blank pages. You decided to keep it. You went back to the inn, now feeling the exhaustion from the fight. Tanjiro had closed the curtains to avoid sunlight getting into the room and lit a torch. The flames crackled and hissed as you sat down. Tanjiro then opened the box and Nezuko crawled out, blinking the sleep out of her eyes. Inosuke ignored her and focused on his two blades, taking off his boar head. Zenitsu was talking with Tanjiro, who seemed to have calmed down a bit. You were just about to talk to him about your findings on the train before you were pounced on by Nezuko.

You fell back a little, adjusting yourself to hold her by putting your hand on her back. She grew back to normal size and lay her head on your chest. You couldn't help but blush a little at her sudden cuddly action. You moved the hand that was on her back to her head and stroked it gently, feeling her long, soft, silky dark brown hair. You then turned to face Tanjiro. “Tanjiro... We need to talk.” Tanjiro looked at you with a confused look on his face before responding, “Hm?” Zenitsu looked at you with a confused expression before realizing what you were gonna talk about. “Inosuke! Let's go out and eat!” Zenitsu said with a smile on his face, Inosuke completely lost interest in his blades and focused his attention to Zenitsu. “YEAHH!! LET'S GO ZERITORO!!!” He exclaimed before grabbing Zenitsu's arm and running with him out the room. “Well that's a new one...” Tanjiro said as he sighed in an amused tone. You chuckled a little before looking him dead serious in the eyes.

“It's about Kanao...” you begin, trying to get straight to the point. Tanjiro's face expression instantly looked cold. “Zenitsu and I went back to the train and... -” your voice breaks, you don't know how to tell him that Kanao might've been attacked by a possible uppermoon. “And what?” he asked. You take a deep breath in before continuing. “Kanao... Might have been attacked by a demon while we were fighting with Kota” you say with a sick feeling in your stomach. You wait for a response... The tension was there, and you felt it. Tanjiro took a deep breath before finally answering. “Well we're going to have to make a plan to track this demon... My nose is really good at smelling for danger and I can smell underground, Inosuke's beast breathing is good for longer distance tracking of entities. Zenitsu has good hearing for screams that seem too far away...” he carried on talking but you focus your attention back to Nezuko. “If this is an uppermoon... Then maybe it can help turn you back Nezuko” you thought to yourself. The night time seemed to have come pretty quickly, all of you were sound asleep at the time since being worn out from the train fight.

Nezuko's POV:

I couldn't fall asleep... My mind has been drifting off to why Y/N looked so sad but hopeful earlier in the morning. Just then I heard something, it was faint but I could hear it. I slowly pulled the curtain away to see someone walking along the streets. He stopped in the town centre and appeared to be looking around the area. Just then I saw his face the moment he turned around. Pale white skin tone with blue stripes running across his face. He had pink short messy hair that stuck out. Those blue stripes ran across most of his body, which was wearing a more dirty colored pink opened up crop top, and greyish white pants. His mouth slowly turned into a almost sadistic smile as he lowered his body into a crouching pose. Then in one quick movement, he dashed forward, destroying most of the buildings. That's when Oni-Chan, Y/N and the other two woke up.

Y/N POV:

The sound of loud snapping of wood and crumbling of rocks woke you up. You turn your head towards the window. Tanjiro got up and crouched down next to Nezuko, “IS THAT AN UPPERMOON?” he whispered. You look outside as well to see what Tanjiro and Nezuko were looking at. Zenitsu came up right after you. “It looks like it... Those eyes spell it out for you basically” you say in a calm manner. “W-Where is Inosuke?” Zenitsu asked from behind you. Inosuke and his boar head, along with his blades were gone. Just then you heard a man scream from outside. He was instantly killed by the uppermoon. Just then you all heard Inosuke's signiture battle cry as he launched himself at the demon. “COME ON WE HAVE TO HELP INOSUKE!” Tanjiro exclaimed before you all ran out the building, just before you left though you grabbed a glass from one of the shelves. The battle had begun. Inosuke was kicked through the air after the first attack and was quickly recovering. Zenitsu stayed back and hid which you noticed but ignored since your plan required him to be ready to run anyways. Tanjiro recieved the first attack and just barely blocked it. You came in with a surprise attack from above but he moved faster and jumped up, rotating his body and kicking you into a broken down house, causing it to collapse on you. You heard Tanjiro scream your name before you passed out. You wake up eventually to someone shaking you. To your surprise... Kanao was sitting above you, shaking you awake. “K-Kanao...?” you ask in a confused but suprised expression. “Sorry I was gone... I was chasing down this demon that tried to attack me at the train” she says before getting up and turning her attention to something else. You look towards the direction she was looking at and saw the uppermoon fighting someone else.

“W-Who is that?” you ask, still in pain. “The flame Hashira” she replied. You slowly got up and scanned the area. Everything looked destroyed, you saw Inosuke, Zenitsu, Tanjiro all together watching the fight. That's when you remembered the glass you had and reached for it. It was still in a usable condition so you put a hand on Kanao's shoulder. “I know I'm probably gonna sound crazy for asking this of you Kanao... But do you think you can cut that demon for it to draw blood...?” you ask in a almost joking kind of way. She stayed silent for a bit but nodded her head. You got up as well, but this time you dropped your katana. Kanao looked at you and you could see the confusion in her eyes but you gave her a reassuring nod. Kanao then searched for an opening, readying her katana. As soon as she attacked, it was quick, she cut off his hand just as the demon was about to strike the hashira. Using your fastest breathing style, you launched yourself towards the hand and got the glass under the demon's severed hand as a drop of blood landed into the glass. You cover the top of the bottle and run towards Tanjiro and the others. “Guys listen to me! Take this bottle to Tamayo's house!” you order before running towards your katana. Just then you noticed the sun starting to come up and felt a wave of relief. You focus your attention back to the hashira and uppermoon fight. The demon was about to give the finishing blow to the hashira, your body felt a instant feeling of fear before you launched your body in between the both of them.

No one's POV:

The demon was stunned with confusion before the pillar pinned him to the ground just as the sun came almost fully out. The demon screamed as he slowly got burned away. The pillar then turned to face Y/N who was laying on the ground with a hole running straight through their body. Tanjiro, Zenitsu, Inosuke and Kanao stared in horror at their friend's almost lifeless body. The pillar picked them up and carried them to a still standing  Y/N...” he said before embracing the others. Nezuko held onto Y/N's body, looking down at their face. Y/N opened their eyes slowly, looking at Nezuko. They smiled, “Don't w-waste your beautiful tears on me Nezuko...” they said while coughing up blood. The others gather around after hearing Y/N's voice. “I want you all to look after one another...” they continue. “Zenitsu... look after Nezuko for me please.” Zenitsu hugs them with tears running rapidly down his face. They smile at Inosuke and Tanjiro, “Y-You can use your healing breathing can't you!?” Tanjiro cried. Y/N didn't answer him, they just closed their eyes and turned their attention to the glass they gave him. “That blood should help lady Tamayo find a cure for Nezuko...” they say before turning towards Nezuko. “I love you, I always have...” Nezuko just looked at them with despair in her eyes. Y/N reached for her bamboo gag and slowly pulled it down, Nezuko leaned her head down and her lips met with Y/N's before their arm fell down and they died in Nezuko's arms...

(Everything after the Mugan train stayed canon to the actual story except Nezuko was a human and a demon slayer)