Demons Among Slayers? (Male Demon Reader x Kimetsu No Yaiba)

Y/N's Promise.

It'd been about 2 months since Y/N began his special training with Sanemi. The two had actually bonded a bit, surprisingly, despite the fact that Y/N had lost over 140 limbs to him.

As the sun shines in through the window, Y/N once again woke up in Shinobu's room. This would often happen when Y/N refused to sleep. Shinobu would drag him to her room, they'd talk for a while, then sleep. Y/N didn't mind, in fact he quite enjoyed it, even though it sometimes led to awkward mornings. This one, however....

Shinobu: "Y/N, there's something-"

Y/N: "Nope. Don't wanna do it."

Shinobu: "........You need to get up eventually, the crow won't stay here foreve-"

Y/N: "The crow can stay here for all eternity, don't give a shit. I'm not gettin up."

......Y/N had decided to sleep in. Despite Shinobu already up and about, he wasn't moving. At all.

Shinobu: "When did you become so lazy??"

Y/N: "Since you started coddling me."

Shinobu: ".....Fine. I'll tell Rengoku's corw to come back another-"

Y/N jolts up and looks at Shinobu.

Y/N: "Rengoku's crow!?"

Shinobu: "Yes....I believe it was holding a-"

Y/N, without letting Shinobu finish, runs out of the room like an Olympic Athlete.

Tanjiro: "Oh! Hello Y/N-"

Y/N: "No time! IT'S HERE!!"

Y/N began running through the halls screaming like a child on Christmas.

Shinobu: "Is....is he..Okay?"

Tanjiro: "You told him about the crow?"

Shinobu: "Yes...?"

Tanjiro: "Prepare to deal with a very excited Y/N."

Y/N comes running back with a cloth, heading straight for the backyard of the mansion.

Y/N: "IT'S FINALLY HERE!! HAHAHAHAAAAAA!"

Aoi: "What the hell is wrong with him?!?"

Tanjiro walks after the hyper-demon, avoiding Aoi's question.

Tanjiro: "You'll see."

With that, everyone joins Y/N and Tanjiro outside. Y/N places the long cloth in one hand, while bouncing with excitement, before using his other hand to slowly unwrap it, revealing Rengoku's re-forged nichirin sword.

Y/N lightly grips the handle of the blade, noting the missing guard, which was gifted to Tanjiro.

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(I noticed something when I was looking at the Flame Breathing Forms for the Mugen Train arc, I don't think we ever get to see Forms 6-8. So, I've decided to create my own.

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Y/N slowly unsheathes the blade, admiring it up close, before turning away from Tanjiro, and taking a quick breath.

Y/N: "Flame Breathing, Sixth Form: Blazing Star!"

Y/N stands still, before slashing 3 times at extreme speeds, the flames resembling a star.

Y/N began giggling to himself, remembering how he got the sword in the first place.

Flashback bitc-

Y/N and Tanjiro were following Rengoku's crow, which was leading them to the Rengoku estate.

Y/N: "Tanjiro? Are you sure you're Ok..?"