The year changed and became January 1906. Half a year had already passed since the Kocho sisters entered the Akatsuki Trading Company's care and began training.
"Hahp!"
A wooden sword split the air along with a shout.
"Too deep! Your speed at striking and retreating is slow!"
Instructor Tsubaki (former Demon Slayer Corps member) deflected the wooden sword diagonally and counterattacked. Though her memories were manipulated, the three-plus years of real combat experience and Breathing sensation ingrained in her body were still sharp.
If she were facing an ordinary swordsman who couldn't use Breathing, they would have been knocked down by just one of her counterattacks.
But her opponent was no ordinary girl.
Claaang!
A dull sound of wooden swords colliding echoed. Surprisingly, it was Tsubaki who was pushed back.
"...!"
Tsubaki's eyes widened. Before her was a mere 14-year-old girl, Kocho Kanae. Just half a year ago, she was a frail girl who couldn't even properly hold a wooden sword, but now she was overwhelming Tsubaki, surpassing equality.
'This child's growth rate... isn't normal.'
I was watching the spar with arms crossed. There was no hesitation in Kanae's movements. Reading the opponent's breathing, predicting muscle movements, and thrusting her sword along the optimal trajectory.
Following her sword path, faint pink petal afterimages bloomed like a heat haze. Even with a wooden sword that wasn't a Nichirin Blade, she had already entered the initial stage of Total Concentration Breathing, Constant.
"There it is, Instructor!"
Kanae stomped the ground. Tsubaki hastily took a defensive stance, but Kanae's sword fluidly penetrated Tsubaki's defense as if dancing.
"Flower Breathing, First Form... [Blossoming·Falling Petals on Flowing Water]!"
A First Form not seen in the original work.
Instantly, the training hall's atmosphere changed. From the tip of Kanae's stepping foot, invisible waves seemed to ripple.
As her wooden sword cut through the air, one sword line scattered like hundreds of petals floating on a river's surface.
It was a thrust yet a slash, straight yet curved. To Tsubaki's eyes, Kanae's sword appeared as dizzying pink afterimages she couldn't even distinguish where they were coming from.
Like flowers falling on flowing water, natural and soft, but the blade hidden within that flow sharply penetrated the opponent's openings like a torrent.
Slithering over Tsubaki's wooden sword raised for defense like a snake, a beautiful yet deadly series of strikes rushing toward vital points along an irresistible trajectory.
A basic form properly showing that Flower Breathing is derived from Water Breathing.
Thwack! Wham!
Kanae's wooden sword struck Tsubaki's wrist hard, making her drop her weapon, and simultaneously stabbed deep into her side, collapsing her balance. Tsubaki lost her balance without even screaming, falling on her rear and rolling on the floor.
"...I lost. Complete defeat, Miss Kanae."
Tsubaki smiled bitterly while rubbing her stinging wrist. She, an 18-year-old legal adult and experienced member, had been overtaken in just half a year by her 14-year-old student.
"Good work, Instructor! Ah, are you okay?"
Kanae released her breathing and extended a hand to Tsubaki. Her face beaded with sweat was bright like sunlight.
Watching that, I nodded. This wasn't a miracle or coincidence.
First was Kanae's own talent. She was a member of the Golden Generation who rose to Hashira position at a young age even in the original work.
She merely met the natural disaster called Douma and died young at just 17, but her ability was at a level matching Hashira of her generation like Shinjuro, Gyomei, Tengen, Giyu, and Sanemi.
Those who fought Upper Moons were mostly adults. Rengoku was in his 20s when he fought Akaza, and Tengen was 23. Compared to the two Hashira without marks, at a much younger age, though he said he was playing while fighting, she was a superhuman who lasted until dawn against Douma, who killed Shinobu in a short time.
Second was precisely our support.
"Today's lunch is special eel rice bowl and bone broth! Come eat quickly!"
Tamamo-no-Mae entered carrying a tray. The meals she and Kiyohime fed the sisters daily weren't simple rice. It was no different from FGO's Bond CE.
They were medicinal concoctions containing magecraft effects that maximized growing children's skeletal and muscle development, and strengthened magical circuits (nervous system in this world).
Eating this until their stomachs burst daily, receiving tutoring from genius swordsmen (Okita, Ushiwaka), and learning Breathing too—there was no way they wouldn't get stronger.
Not comparable to Muichiro who became Hashira at 14, but at this level, she's definitely a genius who'll leave her mark in history.
Kanae had already reached a level where she could face Lower Moon oni without running away and fight. Of course, honestly winning would probably still be difficult.
But the stronger the light, the deeper the shadow.
"Haa... haa... ugh!"
Attention turned to the groaning sound coming from the training hall corner. 11-year-old Shinobu swung a wooden sword as tall as herself until exhausted and collapsed.
"Shinobu!"
Kanae tried to run over, but Shinobu irritably shook off her sister's hand.
"Enough! I can get up alone!"
She got up, sniffling with a sweat-drenched face. Her palms were already bloodied from burst blisters, but what gathered in her eyes weren't tears of pain but tears of frustration.
"Why... why can't I do it."
Shinobu looked down at her slender arms. She ate the same meals as her sister, received the same training. She understood Breathing techniques in her head too. But crucially, she lacked the talent called muscle strength.
No matter how hard she tried, power didn't accompany her sword-swinging speed. Arm strength hopelessly insufficient to cut an oni's hard neck.
Is this also the realm of talent and constitution? Unfortunately, even with our support, compared to Kanae, her muscle growth was noticeably slower. She could be called strong for her age, but that's also just for her age. Still lacking compared to adult men.
"Sister has already gone that far... but I'm still stuck in place. Like this, forget our parents' enemy, I'll die even to a low-ranking oni."
Shinobu's self-esteem had hit rock bottom. Then, a hand patted her head.
"Don't be so impatient, Shinobu."
Shinobu flinched and looked up at me.
"Akira-san... but..."
"Everyone has different innate capacity and form. Kanae has balanced hexagonal talent, but you're different."
I took Shinobu's small, capable hand.
"Your talent isn't slashing. It's thrusting."
"Thrusting... you mean?"
"Right. You're weak in muscle strength, but your instantaneous explosive power and running speed are faster than Kanae's. Like fencing or spearmanship, the speed at targeting and penetrating one point is your advantage."
"But... you can't kill oni with thrusting. You have to cut the neck..."
Shinobu refuted with a tearful face. She's right. Oni don't die unless their necks are severed. But I answered with a smirk.
"So what if you can't kill? Just weaken them enough. And... there are plenty of ways to kill with thrusting in this world."
Poison. I didn't utter that word aloud. I didn't want her to give up on her possibilities as a swordsman yet. Instead, I decided to reveal my own shortcomings.
"And Shinobu. If we're talking about lacking talent, there's no one like me."
"Huh? You, Akira-san? No way, you're lying. Being that strong."
"It's true. I also tried learning Breathing with you guys over the past half year. Secretly trained every night too."
I smiled bitterly and patted my chest.
"But it didn't work. Even increasing lung capacity, circulating blood faster, it was impossible."
Even Muichiro barely shows water effects but can use Breathing, but I can't even do that. Like Genya.
"Ah..."
"The Servants over there are the same. They're already completed shadows of the past. Beings who can't grow anymore, so they can't learn Breathing. In this mansion, the only ones who can use Breathing are you sisters and Tsubaki."
I met Shinobu's eyes.
"So don't be discouraged. Just being able to use Breathing means you have much more amazing talent than me. If muscle strength is weak, use poison, use traps, or become incredibly fast. The path isn't just one."
At my honest confession and encouragement, Shinobu's expression softened considerably.
"...That's unfair. Saying that makes it seem like I was just throwing a tantrum."
"You can throw tantrums. You're still 11. You grow by eating, sleeping, and throwing tantrums."
I messed up Shinobu's hair. She ran away laughing, saying "Ahh, you'll ruin my hair!" Watching her retreating back, I let out a sigh of relief.
This child would later play a decisive role capturing Upper Moon 2 using poison. But rather than burden her with that heavy load now, I just wanted her to grow up healthy.
I don't plan to make her take on that role in the first place.
That night, when I returned to the office after finishing all tasks. Hokusai (Oei), sitting by the window smoking a pipe, called me.
"Master, you're back?"
"Yeah. Did you draw at the main store today? How's the reaction to your new work?"
"Well, as usual, can't sell because there's none. My genius is too ahead of its time."
Oei chuckled, but her eyes were serious, unlike usual. She exhaled pipe smoke and broached the main topic.
"But you know, we had an unwelcome visitor at the main store this afternoon."
"Unwelcome visitor?"
"Yeah. Guys wearing black clothes with the character for 'Destroy' engraved on their backs. About two of them, came in pretending to be customers and were prying about this and that."
My expression hardened.
"Demon Slayer Corps."
"Right. Fortunately they didn't seem to notice my identity or Tamamo's barriers, but they seemed to start taking interest in the Akatsuki Trading Company organization itself. Well, sweeping up money with unheard-of new technologies (ramen, curry), it's natural to be suspicious. They seemed suspicious it might be an oni's funding source."
The concern had materialized. Was it because we grew too conspicuously? Or related to Tsubaki's disappearance?
There are cases like Gyokko selling pottery for money, and Douma operating a cult. Are they checking just in case?
"What shall we do, Master? Kill them outright? Or kidnap and brainwash them like last time?"
Oei made a throat-slitting gesture with her hand. I shook my head.
"No. Provoking them now would only turn their suspicion into conviction. Pretend not to know for now. Act as if we're just lucky merchants who are good at smelling money."
"Hmm, got it. Annoying guys have gotten tangled up."
Oei picked up her brush again. I looked out the window. Tokyo's night sky was still dark, but it felt like numerous eyes were watching us from within that darkness.
Muzan's oni, and the Demon Slayer Corps.
A third force pursued by both sides. The tightrope walk had only just begun.
"First thing tomorrow, I'll have Tamamo increase the barrier strength. And..."
I opened the desk drawer, took out a pistol, and fiddled with it.
"Just in case, we should secure more guns too. Can't we get a minigun somewhere? Nobbu doesn't have a minigun since she's not an Avenger."
Winter of January 1906. Tokyo's cold wind seeped through the Akatsuki Trading Company's door gaps.