I'm From a 19+ World, and Today I'm Still Giving Everyone Who Watches Demon Slayer Emotional Damage

Tip: I'm planning to write this work as a sweet story with a knife hidden inside. Whether it's the Demon Slayer Corps or the demons, only a handful will survive in the end. Either both sides will perish together, or one side will win a costly victory. The demons will use underhanded methods, and the Demon Slayer Corps will be stronger too. The early and middle parts will be fine, and I'll maintain a surface-level harmony. But once we reach the middle-to-late part, there will be a lot of heartbreak. No one is safe, whether they're from the original work or among the sinners. The original characters won't find redemption, though some will fare better and others will suffer even more. If you're a devoted fan of any character and can't accept that, please don't read this, so you don't harm your mental or physical well-being. Some demons may temporarily escape justice, but in the end, almost all of them will be brought to account at once. I want to write a story with the feel of the original, about a true Demon Progenitor and the Demon Slayer Corps, whose mission is to hunt demons. I hope my work lets you feel as though you're at the cinema. After you've cried and laughed, after the final curtain falls and the audience leaves, I want you to remain in your seat and watch the behind-the-scenes footage of the actors climbing back to their feet in little groups and chatting about what to eat tomorrow, before you leave satisfied.

Haha... So playing the Project Moon trilogy and then watching Demon Slayer makes me transmigrate? You're something else. I really can't thank you enough...

What do you mean this is the dark reboot? What do you mean people are reading it? What do you mean the kids watching are going to get hit with knives? What do you mean the more knives the better? Huh?

And... why do your words sound so familiar?

What do you mean... you can make calls across worlds? Extract the personalities from mirrors?

Haha, kids, am I going to win?

I should've known better than to play games. I should've studied psychiatry instead.

Well... whatever... let's just leave it at that...

Wait? What do you mean I'm Muzan? What do you mean everything that should happen is bound to happen? Oh, I...

>>A story about a child who escaped blood thicker than water, experienced many adventures alongside her companions in the Demon Slayer Corps, and whose dreams and hopes never came to an end: the story of Don Quixote of the Demon Slayer Corps.

"Hi there, newcomer! I'm Don Quixote, a demon-slaying swordswoman under the Master. You'll be following me. Let me teach you how to be a righteous hero!!! Slay the evil demons!!!" The yellow-haired girl, carrying a knight's lance and a sword, shouted excitedly at Tanjiro.

"Tanjiro... My justice is right here!!! I absolutely will not back down!!!" In the eyes of Tanjiro, who was being carried away by his teammates, all that remained was the figure of the yellow-haired girl, covered in wounds, charging at the Demon Progenitor with her knight's lance. "Run, Nusinande! Justice always wins!!!"

>>A story about the demon who could never escape blood thicker than water, who prepared a grand feast for her family, tormented by hunger and pain, executed the father who betrayed the children, and bore all the guilt on her shoulders, tears of blood in her eyes.

"Tanjiro Kamado, your path ends here. You shall not pass." In the Infinity Castle, Tanjiro looked at the person who should have died long ago. His chest was already filled with rage. The yellow-haired girl, each blood-red eye marked with a character, held a refined hard-blood spear and stood in Muzan's defense. "Demons eating humans... is only natural..."

"And now... it's time to enjoy dinner." The girl, who no longer called herself Don Quixote in front of the Demon Slayer Corps, bared her fangs and freely gave voice to her true nature before her former comrades. She declared to the comrades who had now become demons, "Go slaughter humans, bathe in their blood, follow your hearts, and revel to your heart's content!!!"

"As a father, for my family..."

"I'm entrusting my family to you..."

>>If the fake is real, then white jade becomes a bed and gold a horse.

"Ah~ It's you. So this time you're the one who became a Hashira. Then let me introduce myself again. I'm the strategist who advises the Masters of every generation. You can call me Hong Lu..." The boy with jade-colored eyes smiled gently as he led the newly promoted Hashira to the Master's residence. When the Hashira asked him a seemingly rude question, the smiling child didn't mind. "Huh? This eye? The former Masters gave it to me. It doesn't look that strange, does it? Hehe~ The Masters are such kind people..."

"Hehe~ It seems... my path, my watch... have come to an end too..." After demons attacked a village, the Hashira arrived to find the strategist covered in wounds, refusing to retreat as he fought to the death with a guandao in hand, shielding the swordsmiths as they escaped. One eye shimmered with jade-colored light. Despite everyone in the Demon Slayer Corps doing everything they could to treat him, the child inevitably fell into a coma from which no one knew when he would awaken. In the end, he did wake up. His wisdom still shone as brightly as his jade eye, bringing the Demon Slayer Corps nearly limitless wealth and strategies to use against the Demon Progenitor. On the surface, everything seemed as it had before, but he never stepped outside his room again...

>>If the fake is false, then every word is a lie.

"Ah, what a mess..." When they arrived, they saw their old friend, pinned through the body by a massive blood-red wedge in the fire the Master had personally started, yet still standing with a guandao and holding his belt as he waited for them. As the Hashira looked at him with grief, fury, and disbelief, and asked questions they could no longer hold back, dirty blood continued to flow from his empty left eye, staining his blue bandage deep crimson. He laughed freely, giving vent to his every joy and sorrow: "When falsehood is taken for truth, truth itself becomes false. When nonbeing is taken for being, being itself becomes nothing."

When the hats hiding the identities of the two people called the leaders were knocked off in the chaos of battle, everyone's fury reached its peak. But the former strategist simply planted his guandao down hard. While everyone stared, stunned by the two leaders' faces, he grabbed the hairpins of the Rooster and Snake leaders and calmly gave his order: "Make them understand... what fate awaits those who dare raise a blade against their ruler... even if millions must bleed..."

"Hehe~ In the end, it was all a dream. All the worlds are empty."

"I would cover this clear sky with my thoughts. I would offer up this body, and let all the blood spill upon the earth..."

The demons given the title of Lower and Upper Ranks would never forget what the being called Muzan said to them...

"I'll light the way ahead for you. Go on and do as you please, in whatever way you wish."

Written on September 28, 2025

Theme: Remain forever trapped in the past, and create a cycle