Demon Slayer Corps Headquarters, Infirmary.
"You said Demon Slayer Mark?" Michikatsu looked at his younger sister with surprise.
To be precise, it was the red Demon Slayer Mark on his younger sister's cheek.
It actually bore some resemblance to Yoriichi's.
Mizuki nodded slightly. "I almost died at the hands of a demon then, but the suddenly awakened Demon Slayer Mark saved my life."
"From my understanding, it should be an ability that can only be mastered after the body breaks through its limits."
Michikatsu stared at Mizuki in shock, completely bewildered by her words.
Before Mizuki, both the Demon Slayer Corps and Michikatsu had only considered the Demon Slayer Mark on Yoriichi's forehead to be a natural birthmark.
Until now, when Mizuki also awakened the Demon Slayer Mark.
After a moment of silence, Michikatsu clenched his fist: "You said your body became stronger?"
"Yes. Although I don't know the principle behind it, I can clearly feel the increase in strength."
Mizuki, who had been resting for a few days, had recovered from her weakness and could clearly feel the changes in her body.
Michikatsu suddenly stood up, gripping the hilt of the blade at his waist: "Come with me to the training ground."
He wanted to verify this conjecture himself.
How could something so absurd be possible?
The physician nearby quickly said, "That won't do, Miss Mizuki's body hasn't fully recovered yet."
"I think I'm already fine... *cough* *cough*." Mizuki said with a smile, her serene expression shifting slightly as she couldn't stop coughing twice.
The physician sighed: "Your lungs suffered severe frostbite, which cannot be completely eradicated with current medical standards. The use of your Breathing Technique will likely be affected."
Michikatsu frowned slightly: "What happened?"
Mizuki shook her head: "I was just tricked by that Demon."
Those who awaken the Demon Slayer Mark will not live past twenty-five.
Knowing this fact, Mizuki didn't seem to care about the lung ailment.
Moreover, compared to the Swordsmen who had just learned a Breathing Technique only to die tragically at the hands of demons, she was much, much better off.
At least, she was still alive.
Being able to return alive from the battlefield was lucky enough.
Seeing this, Michikatsu couldn't force her anymore. "Then rest well."
Having said that, he was about to turn and leave.
"Wait." Mizuki got up from the sickbed.
The physician lady hurriedly tried to step forward and help her.
Mizuki declined her kindness, saying, "Miss Physician, you should be aware of my condition."
The physician paused, then sighed: "I will try to find a solution for your lung issues."
"Please try to avoid strenuous exercise."
"Thank you." Mizuki smiled slightly, then turned to Michikatsu and said, "Big Brother, let's go to the training ground."
Michikatsu frowned as he looked at her, remaining rooted to the spot.
Mizuki tilted her head: "What's wrong?"
"..." After a long silence, Michikatsu suddenly spoke, "When did you become so gentle?"
It inexplicably gave him the feeling that a dying person's words are kind.
"..." A vein slowly pulsed on Mizuki's forehead, and she forced out a deathly smile. "Oh, is that so? So Big Brother is the type who feels uncomfortable if he isn't scolded?"
"If you had said so earlier, Mizuki could curse at you all day long."
Her own words gave her goosebumps, but as long as she could disgust Michikatsu, it was a victory.
Michikatsu ignored her this time and turned to leave the ward.
Mizuki took a deep breath.
Calm down, calm down.
This damned sourpuss, she was going to use a full set of moves to defeat him today!
The training ground Michikatsu spoke of was not the Demon Slayer Corps' training ground, as people often used it, and Michikatsu disliked being watched.
The training ground he referred to was the back mountain of the Demon Slayer Corps.
The three siblings often honed their Sword Skills there.
Upon arriving at the training area, Mizuki set down her nichirin blade and reached for the wooden sword placed nearby.
"Use a real blade."
Michikatsu's voice interrupted her movement. Mizuki paused for a moment, slowly drew her nichirin blade, and stood opposite her older brother.
Mizuki raised her eyes slightly, looking at Michikatsu, who had also drawn his nichirin blade.
"Come on."
As soon as the words fell, two voices sounded simultaneously.
"Moon Breathing, First Form: Dark Moon - Evening Palace."
An Iai Slash, too fast for ordinary people to see, collided at this moment, and the blade let out a sharp, mournful cry.
Michikatsu's pupils contracted slightly, and the arm holding Mizuki's nichirin blade trembled faintly.
He was actually being overpowered... Men's bodies are inherently stronger than women's.
This was an undeniable fact.
This was also why Michikatsu still didn't have high hopes for Mizuki even after she became a member of the Demon Slayer Corps.
It wasn't that he hadn't sparred with Mizuki before; he usually defeated her easily and had never experienced such immense pressure as today.
And she was clearly still using the Breathing Technique she wasn't proficient in.
It was as if she had been reborn.
"Moon Breathing, Second Form: Pearl Flowers in the Moonlight!"
"Water Breathing, Fourth Form: Striking Tide!"
Back and forth, all of Michikatsu's attacks were blocked by Mizuki.
Was it not just Yoriichi, but Mizuki too, who was going to leave him behind?
The more unwilling Michikatsu felt, the more erratic and disorderly the nichirin blade he wielded became.
Mizuki, whose physical strength had greatly increased, calmly defended against her older brother's fierce attacks.
She wasn't an idiot. Even though she hadn't read the manga or thoroughly understood Michikatsu.
But after twenty years of living together, she had long seen through Michikatsu's jealous nature.
He was constantly jealous of Yoriichi's talent. Or rather, he could accept the fact that he was inferior to others, but he absolutely could not accept that the people surpassing him were his own younger brother and younger sister.
Especially his twin brother.
He was jealous of the talent belonging to his own family.
"*Cough*..."
The moment Mizuki's breathing was disrupted due to her lung ailment allowed Michikatsu to seize a chance.
"Moon Breathing, Sixth Form: Perpetual Night, Solitary Moon - Incessant!"
Several rapid crescent slashes shot toward Mizuki.
The greatest strength of Moon Breathing lies in the fact that the slashes are accompanied by more detailed crescent slashes.
They can easily cover a large area.
"Hiss~"
Mizuki calmly adjusted her breathing, exhaling a faint white aura.
"Snow Breathing, First Form: Tornado!"
The white tornado, mixed with a chill, swept away all the incoming crescent slashes.
At the same time, Michikatsu, who had never witnessed Snow Breathing, was hastily caught in Mizuki's Sword Form and swept into the air.
"Snow Breathing?!" Michikatsu, losing his balance mid-air, was deeply shocked.
Not just strength, but even creating her own Breathing Technique... Didn't this mean that Mizuki's talent was exactly the same as his?
If he couldn't even surpass his own younger sister, how could he possibly surpass that person!
The frantic tornado constantly struck Michikatsu's body. Since this wasn't a fight to the death, Mizuki was using the back of her blade.
The anxiety of defeat combined with the jealousy that was practically gushing out caused Michikatsu's body temperature to continuously rise, and the frequency of his pulse rapidly soared.
"Moon Breathing, Fifth Form: Moon Spirit Calamity Vortex!"
Michikatsu's body spun mid-air, generating a massive vortex-like blade around his swinging nichirin blade, repelling the tornado.
The two forces collided and completely canceled each other out.