What—
Rengoku Kyojuro's eyes widened.
Before he could react, Song Yue had already shaped her blood into a thin needle. It pierced through his haori and sank deep into his shoulder, injecting a blue serum.
"Hahaha! Fool! You actually think you can kill Lord Muzan? How naïve!"
Song Yue laughed wildly.
A freezing chill spread through Rengoku's body. His thoughts slowed. His limbs felt heavy.
At that exact moment, the now-giant Hantengu delivered a brutal kick.
Rengoku raised his blade to block—
Boom!
Even so, he was blasted backward, smashing through the wooden wall of a nearby house. Timber splintered. Dust filled the air.
For a moment, his condition was unknown.
From the sidelines, Ryuya calmly analyzed the situation.
He now fully understood Song Yue.
Her love for Muzan was pathological.
Possessive.
Unstable.
Her hostility toward Hantengu earlier made perfect sense.
As for her Blood Demon Art—
It consisted of three primary abilities.
First: Syringes.
Three types of serum—
Green for healing.
Red for enhancement.
Blue for weakening.
Second: Bandages.
White wrappings capable of restraining opponents, laced with paralyzing toxins.
Third: Mist Puppets.
Formed from her tears.
The puppets themselves lacked offensive power, but their numbers increased when destroyed. And she could instantly swap places with them.
A versatile, layered Blood Demon Art.
Combined with her obsessive devotion—
Ryuya was extremely satisfied.
This woman could easily fill Muzan's need for a new Lower Rank Two.
And she could serve Ryuya's own plans as well.
A personal "nurse" by Muzan's side…
Imagine the possibilities.
A dangerous idea quietly formed in Ryuya's mind.
"Lord Muzan!"
After driving off Rengoku, Song Yue rushed back, cheeks flushed with anticipation, clearly waiting for praise.
Lower Rank Three and Hantengu exchanged confused glances.
Lord Muzan?
Isn't that Young Master Ryuya?
But after thinking it over, if they had never seen Ryuya before and didn't know he existed, perhaps they would have made the same mistake.
"Kiyo. Hantengu. Go check whether Rengoku Kyojuro is dead."
Ryuya dismissed them casually.
"Yes!"
Kiyo obeyed immediately. Hantengu shot Song Yue a resentful look before following.
Once they were gone—
"Song Yue. Come closer."
Ryuya smiled faintly.
"O-Okay, Lord Muzan!"
Blushing shyly, Song Yue stepped forward.
When she was within reach—
Ryuya struck the back of her neck.
Her eyes rolled back. She collapsed instantly.
Ryuya caught her before she hit the ground.
Then he activated his Blood Demon Art.
He needed to alter her memory—specifically the parts where she called him "Lord Muzan."
If he brought her before the real Muzan while she continued mistaking him for him, things could get… unpleasant.
Ryuya's Blood Demon Art allowed him not only to erase and implant memories—but to examine them.
He began flipping through her past.
Song Yue had not been born into poverty, nor wealth.
She grew up in a respectable household.
Persistent.
Diligent.
She believed effort must yield equal return.
She loved helping others and admired doctors who eased suffering.
By chance, she married one.
At first, they ran a modest clinic together. It wasn't extravagant—but it was enough.
Then slowly, her husband changed.
He drank.
Gambled.
Beat her.
Called her useless.
Eventually, she discovered the reason.
He had taken a female patient as a lover.
The woman who frequented their clinic.
The woman Song Yue herself had treated.
Something inside her shattered.
She had given everything.
Her love.
Her devotion.
Her labor.
Why had it not been returned?
Why had her love been given to someone else?
It was unfair.
So unfair.
She begged.
Kneeled.
Cried.
She didn't want wealth.
She didn't want status.
She only wanted her love back.
She couldn't understand why the patient—whom she had helped so sincerely—would repay her kindness with betrayal.
That night, during a violent storm, her husband threw her out.
Rain soaked her thin clothes.
Tears mixed with water.
Then came the gamblers.
Her husband owed them money.
They threatened him—if he didn't pay, they would violate Song Yue as compensation.
She screamed for help.
Begged.
The gamblers pounded on the door.
Her husband never came out.
And so—
They turned their attention to her.
As they tore at her clothes in the rain—
A man passed by.
Black suit.
Long black hair.
Rose-colored eyes.
Holding an umbrella.
Kibutsuji Muzan lifted her chin gently.
And gave her blood.
On the night she transformed—
She slaughtered the gamblers with surgical precision.
As for her husband and the mistress—
She bound them to operating tables.
Made them watch as she dissected them piece by piece.
Their screams echoed through the clinic.
Muzan watched.
Amused.
He loved seeing humans destroy each other.
That hysterical despair.
That delicious cruelty.
When it was over, Song Yue stood drenched in blood.
Smiling.
She finally understood.
Love is not begged for.
It is taken.
Claimed.
Earned through power.
And she had found her true love.
Muzan.
Her savior.
Before leaving, he told her only one thing:
"Become stronger for me."
Those words became her life.
She trained.
Devoured.
Evolved.
All to become worthy of him.
All to stand at his side.
For love—
She would abandon everything.
When Ryuya finished reviewing her memories, he felt a faint sigh escape him.
In life, she had been pitiful.
Now, her existence was sustained purely by obsession.
A twisted, morbid love.
Ryuya understood her now.
If that's the case…
I'll take you to see Muzan.
Let your unrequited love reach its conclusion.
After editing her memories to remove any confusion between himself and Muzan, Ryuya prepared to summon Nakime.
He intended to request transport to the Infinity Castle.
But before he could even speak—
The sound of biwa strings echoed through the void.
The world distorted.
Space folded.
And in an instant—
He and the unconscious Song Yue were transported to the Infinity Castle.
Meanwhile—
Within the shifting corridors of the castle—
Muzan and Kochou Kanae were already waiting for the arrival of his son, Ryuya.
...
Author's Note:
The full completed version of Demon Slayer: Son of Muzan (Completed) is now on Patreon!
🔥 I also have additional 18+ fanfics available for readers who enjoy exclusive mature stories. 😉
1. Dragon Ball: Oolong's Sex Adventure
2. Elements of Lust – ATLA & Korra Mixed Smut
3. Doraemon: Filtering with Nobi Tamako
4. The Naive Me Who Became Someone's Everyday Secret
5. High School DxD: Rias Gremory, the Phenex Bride
6. Versatile Mage: Awakening the Succubus System
🔗 patreon.com/Shadow_demon_007
Thank you all for your support and love for this story 💙