So I slightly change the story, so non-manga readers wouldn't be spoiled.
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"Huh me?" you asked as you blinked at Tanjiro and the others
"Please! We have no one to asked " Tanjiro pleaded as they all await your answer.
"eh sure, I'm not busy anyway" you said as you accept going on mission with them, but what you didn't expect was going to the red light district and acting undercover.
"Is this really necessary? I think it doesn't suit me at all" you said as you got out of the dressing room, once their eyes land on you, they all have a blush on their face as they took in your appearance.
your usual messy hair was brush and flowed down all the way to your waist, your pale face was beautifully applied with make up and you wearing an elegant kimono that greatly compliment your make up and hair.
"PLEASE MARRY ME, (Y/N)-CHAN!!" Zenitsu shouted as he kneeled down and wrap his hands on your waist, Tanjiro immediately pulling him away.
"Shinazugawa-san would kill you Zenitsu" Tanjiro said as he pulled away Zenitsu who had a realization. that's right, Sanemi and you were going out, it was a shock at first for everyone but later on they got used to it as you and Sanemi was really never a fan of PDA.
"You look really beautiful (Y/N)-chan" Tanjiro compliment
"Really? Thank you Tanjiro but I think Inosuke looks so beautiful" you chuckled as you saw Inosuke wearing make up and wearing a Kimono.
"I WOULDN'T LOSE TO YOU!" Inosuke shouted as he pointed at you, as you were giggling and chuckling a flash come from the other side of the room. as you look at it, It was Tanjiro who was holding a camera on his hand.
"What was that for?" you asked
"Nothing" he grinned, you shrug it off and help Zenitsu tie his hair.
Meanwhile on the demon slayer headquarters, the Pillars had gathered for a meeting, as they wait for Oyakata-sama to arrive others converse random topics while a heated glaring contest was happening between Giyu and Sanemi, mostly Sanemi.
"By the way I haven't seen (Y/N), where is she?" Mitsuri asked, as she look around for you.
"She went on a mission with Tanjiiro and the others" Shinobu gently said as she had her usual smile on her face.
"oh I s-"
"WHAT THE HELL DID YOU JUST SAID?!" Mitsuri was interrupted as Sanemi's voice boomed in the whole estate.
"nothing" Giyu calmly replied as Sanemi was seething with anger, If you where here, you would mostly stop him and distract him from slicing Giyu.
"YOU BASTARD I'LL CUT YOU TO PIECES!" Sanemi angrily shouted as he was about to draw his sword but a raven flew down and landed on his shoulder, almost sweating because of the murderous aura Sanemi was emitting.
"What the hell ?!" Sanemi said as he glare at the Raven, It was Tanjirou's Raven, a piece of paper tied to it's leg.
"A letter for Shinazugawa! A letter for Shinazugawa!" the Raven repeated as Sanemi angrily took the letter and opened it.
Everyone was staring at him as they wait for what the contents of the letter was, instead they didn't expect to see Sanemi blush and look so vulnerable, even Giyu look at him in disbelief.
"What the hell This so damn cute" Sanemi whispered to himself as he try to hide his blush with the back of his hands, the Raven didn't bring a letter but a picture, it was a picture of you looking so innocently at the camera, wearing make up and kimono.
"Am I seeing right?" Uzui asked
"Shinazugawa is...." Obanai said
"blushing" Muichiro continued as they all look with astonishment to Sanemi.
"I'M NOT BLUSHING! ALL OF YOU FUCK OFF!" he yelled as he turned around to leave while covering his red face.
"What did the letter contain?" Gyomei asked as he block Sanemi and was about to took the letter on his hand, but Sanemi pulled it away and stuffed it on his uniform.
"Don't! no one is allowed to see but me!" he seriously said as he walk away to calm down his beating heart.
a few days later, after the Mission you immediately go to Sanemi's estate to visit. as soon as you step inside Sanemi engulf you in a hug, startling you a little.
"What's the matter?" you asked a little confuse at his behavior.
"You!" he whispered
"me?" you asked
"...How could you let others see this without my permission" he said as he took out a picture and showed it to you.
"why do you have this?....Tanjiro" you said as realization hit you, he sent Sanemi the picture he took.
"Next time don't look so cute in front of other men or I'll gauge off their eyes" he seriously said making you chuckled.
"Oh Sanemi, I just love you so damn much" you said as you engulf him in a hug once again.
"You better be, because I love you so damn much too"
~•~
I'm not even sure if there were already cameras back then. Just pretend there is.