Demon Slayer: Starting with the Kingdom

Demon Slayer: Starting with the Kingdom

Author: A Black Bird

Brief introduction: (The rating has just been released and will gradually increase.)

[Female protagonist + no system + demons + Muzan's side + Yaiba the Movie: The Pillar Slayer]

Years later, when Mitsuha Tsugikuni faces the final battle against the Demon Slayer Corps in the Infinity Castle, she will recall that morning when she took Yoriichi to watch Miku Shō practice his swordsmanship.

Perhaps it was from that day on that the fate of the three siblings, Ji Guo and his sister, was already sealed...

My name is Mitsuha Tsugikuni. I am the younger sister of the Son of God, the Upper Moon One of the Twelve Demon Moons, the best secretary of the Demon King Muzan, the one who stole the power of the gods, the manipulator of fate, the only usurper in the world, and the nightmare of the Demon Slayer Corps for hundreds of years.

At the same time, he is also the one who ends the thousand-year obsession of the Ubuyashiki family.

"People die every moment in this world. Does it matter who kills whom or who is killed?"

"A brilliant resolve! Then let me see if you can break free from this prison called fate!"

"Alright, let's finish this quickly, I have to rush back for a meeting..."

P.S.: The female lead is a demon on Muzan's side, not an undercover demon who is physically in the demon camp but mentally in the Demon Slayer Corps.

Chapter 1 Mitsuha Tsugikuni

Infinite City, the Great Battle

"Huh...huh..."

Blood streamed down his cheeks, staining his vision crimson.

His body was already at its limit, and his hands holding the sword trembled uncontrollably. Tanjiro tried to open his eyes wide and stared intently at the kimono-clad figure standing opposite him.

Mitsuha Tsugikuni was born in the distant Warring States period and is the younger sister of Yoriichi Tsugikuni, the legendary "Child of God".

She is the Upper Moon One of the Twelve Demon Moons, the sole inheritor of the "Child of God" swordsmanship, the strongest demon in the world besides the Demon King Muzan, and a nightmare that the Demon Slayer Corps has never been able to defeat in hundreds of years.

Inside this small dojo, conjured by Nakime's Blood Demon Art, the surrounding area was filled with the severed limbs of Demon Slayer Corps swordsmen.

Some of them Tanjiro knew, and some he didn't.

Mitsuha Tsugikuni...

How many Demon Slayer Corps swordsmen have you stopped here? And how many of my comrades have you killed?

They, they...

"Uhhhhh!!"

Images of his former comrades flashed through his mind, and anger and sorrow filled his chest at the same time, causing tears to well up in his eyes. Tanjiro stared intently at the kimono-clad figure opposite him, roared, and swung his sword forward once more.

He must win, he absolutely has to win!

He wants to kill her, he absolutely must kill her!

On a sunny morning several hundred years ago during the Warring States period, the sun was shining brightly.

In that town ruled by the Tsugikuni Kingdom, a girl named Mitsuha Tsugikuni ran quickly down the corridor of the mansion.

She stopped in front of the room in the corner of the courtyard, turned around to look around, and after making sure that no one was nearby, she carefully pushed open the small door at her feet, bent down and climbed inside.

“Brother Yoriichi, look, this is a hairpin that Mother made for me.”

The room was empty and somewhat dilapidated. On the bedding in the corner, the boy who had been lying quietly on the bed staring at the ceiling heard the sound and slowly got up and looked over.

The boy's eyes were clear yet empty. He had long, deep red hair and a strange, flame-shaped scar on his left forehead.

The boy's name is Yoriichi Tsugikuni, and he is Mitsuha Tsugikuni's second older brother in this life.

That's right, Mitsuha is actually a reincarnated person.

In her previous life, she was born with a serious illness and died early, struggling in her sickbed.

When she opened her eyes again, she found herself reborn as an infant into a family known as the Kingdom of Succession.

This is a powerful and noble family. Mitsuha's father is a daimyo who rules a town, and her mother is the daughter of a daimyo from a neighboring country.

Mitsuha is the eldest daughter and youngest child in the family. She has twin brothers, Kokushikatsu Tsugikuni and Yoriichi Tsugikuni.

The family of five was well-off, with living parents, an older brother, and a healthy woman free from illness...

For Mitsuha, this was truly an unbelievably wonderful dream family.

If there's anything wrong with her, it's probably her two twin brothers.

In this world, twins have always been seen as an ominous sign, as they could potentially trigger inheritance disputes within families.

Therefore, when Yoriichi's older brother, who had a strange scar on his forehead, was born, his father, who was worried about this, wanted to kill him on the spot.

It was only after his mother, Akane, desperately tried to stop him that his father finally changed his mind and allowed Yoriichi to stay in Tsugumi Province on the condition that he be sent to a temple to become a monk as soon as he turned ten.

Even so, Yoriichi's elder brother merely "remained" in Tsuguhiko Province.

In terms of daily food, clothing and other necessities, Yoriichi, who is also a male heir to the state, is not only completely inferior to his older brother Miku, who is being groomed to be the heir, but he is also far inferior to his younger sister Mitsuha.

Not only did she never receive a proper education growing up, but she also had to live in this dilapidated little house in the corner of the mansion, wearing coarse cloth clothes, and she wasn't even allowed to go out freely...

For this reason, from a very young age, Mitsuha would often sneak into this small room to chat with her older brother Yoriichi.

Of course, it wasn't just her; sometimes Yan Sheng's older brother would come along too.

The three siblings often read books together in this small room, practice writing, play suguro (a card game), and even chat about the future.

Although most of the time it was only Mitsuha and Miku who were talking, Yoriichi would just stare blankly at the two of them with her clear, empty eyes, and only occasionally would she reply with a word...

Mitsuha was already used to it.

“Brother Yoriichi, look, this is it.”

Kneeling down beside Yoriichi, Mitsuha gently removed the hairpin from her hair and presented it to Yoriichi.

The hairpin is made of jade, entirely emerald green, with a head decorated with three green leaves, simple yet beautiful.

"My mother said that these three leaves not only represent my name, but also the three of us siblings."

My mother also said that the middle section is me, and the two sections on the sides are my elder brother Yan Sheng and my elder brother Yuan Yi.

Although my two brothers are temporarily separated, as long as I, their younger sister, am there to mediate and hold their hands, the three of us will always be of one mind.

Only by supporting each other in this way can the three of us siblings be happy forever, and can our country continue to prosper...

Brother Yoriichi, what do you think?

Listening to Mitsuha's cheerful story, Yoriichi didn't reply, but he still smiled and nodded slightly.

"Ah! Right, right! And this too!"

As if by magic, Mitsuha suddenly took out a pair of sun earrings from her sleeve.

"These sun earrings were made by Mother for you, my elder brother, Eiichi."

My mother also said that this contains all the prayers she has offered to Amaterasu Omikami on your behalf over the years, and it will surely protect you, Yoriichi, throughout your life with peace and safety.

Mitsuha placed the earring into Yoriichi's still-dazed hand, stood up, and smiled as she extended her hand to him, saying:

"Alright, Brother Yoriichi, let's go. Father went out to inspect the city early this morning. Mother asked me to take you to have breakfast."

Because of his father's dislike for Yoriichi, when his father was home, he not only forbade anyone in the family from having any contact with Yoriichi, but even during mealtimes, he only allowed Yoriichi to stay alone in this small room.

Only when their father is away, like today, do the three siblings have the opportunity to sit down and eat together.

"Hey! Drink! Again!"

"Well done! Young Master Yan Sheng, please continue!"

Just as Yoriichi took Mitsuha's hand and stood up, a shout from Kokusatsu suddenly came from the courtyard outside.

Seemingly curious about the sound, Yoriichi, puzzled, finally spoke his first words of the day.

"What is my elder brother doing?"

Chapter 2 Where it all began...

"Brother Yan Sheng is practicing swordsmanship."

Seeing that Yoriichi was interested, Mitsuha immediately explained:

"A few days ago, during a meal, my elder brother Yan Sheng told our father about his dream of becoming a samurai in the future."

Father was very pleased, so he arranged for one of his subordinates to teach Yan Sheng swordsmanship.

These past few days, Brother Yan Sheng has been getting up before dawn every day to train with this master, and his hands have been worn raw several times..."

As Mitsuha spoke, she let out a soft sigh.

Upon hearing this, a flicker of curiosity flashed in Yoriichi's previously empty eyes.

After a moment's hesitation, he looked up at his younger sister and said:

"I want to see it."

"……Eh?"

This was the first time Mitsuha had ever heard the words "I want..." from her second older brother.

After a brief moment of surprise, she quickly nodded in response:

"Alright! Since we still have some time before breakfast, let's go watch Brother Yan Sheng practice his sword!"

With that, Mitsuha immediately led Yoriichi out of the room and quickly walked toward the courtyard where Miku was practicing his swordsmanship.

But after taking only two steps, she suddenly stopped and looked back, as if she had suddenly realized something.

Behind him, Yoriichi still had that blank expression, head down, eyes vacant.

Where is the demeanor of an elder brother in that expression?

Seeing this, Mitsuha sighed helplessly.

But immediately, she smiled and stepped forward. Under Yoriichi's slightly puzzled gaze, she suddenly reached out and hooked the corners of his mouth, then pulled them up forcefully.

"You should smile more, Yoriichi-nii."

Looking up at her second brother, who was still full of doubt despite her forced smile, San Ye smiled and said:

"If you're always frowning, even if you have good luck, it will eventually drive you away, right?"

Yoriichi was stunned.

Looking at his younger sister trying so hard to make him happy, his eyes suddenly welled up with tears for some reason.

He is indeed a very happy person.

Even though his father didn't love him, his mother, brother, and sister all tried their best to care for him in their own ways...

Standing there, staring blankly at Mitsuha who had already turned and walked away, Yoriichi's gaze gradually softened, and the corners of his mouth unconsciously turned up.

They were all treasures he cherished.

"Brother Yoriichi? Stop standing there daydreaming, let's go!"

Looking at Mitsuha waving and beckoning to him from the end of the corridor, Yoriichi smiled and nodded slightly.

At only six years old, Mitsuha Tsugikuni was as beautiful as a budding flower.

Unbeknownst to Yoriichi Tsugikuni, he was already looking forward to seeing this flower bud bloom.

Because at that moment, he had no idea that the final appearance of this flower bud would be so ugly...

When the brother and sister reached the courtyard, they witnessed the tragic scene of their elder brother, Yan Sheng, being knocked to the ground by his swordsmanship master in one move.

Looking up and seeing his younger siblings walking towards him, Yan Sheng was taken aback for a moment, then quickly stood up and smiled somewhat embarrassedly.

"Yoriichi, Mitsuha..."

“Brother, Brother Yoriichi said he wanted to see you practice swordsmanship, so I brought him here.”

Mitsuha explained, and then gave Yoriichi a gentle push on the back, propelling him forward.

"Oh! Isn't this perfect!"

Seeing Yoriichi looking down at his toes, seemingly somewhat timid, Yan Sheng smiled and offered him the bamboo sword.

"Since this is the opportunity, Yoriichi, why don't you try practicing too?"