It was the darkest hour of the night.
Dawn was still a ways off.
Under the cover of darkness, the girl's attack sliced through the night like a streak of color—the most brilliant flash in the pitch-black sky.
"Insect Breathing… Dragonfly Dance… Compound Eye Hexagon!"
Shinobu dropped from the branch like a butterfly in flight. Her uniquely shaped Nichirin Blade thrust forward at blinding speed.
Among all the Hashira, Shinobu's physical strength was unquestionably the weakest. She couldn't even cut off a demon's head with a normal slash—some ordinary Corps members were stronger than her in raw power.
That was why she had created her own Insect Breathing, derived from her sister Kanae's Flower Breathing. She had abandoned the idea of beheading demons. Instead, she coated her blade with self-developed poisons and killed by stabbing the blade into her target and injecting lethal toxins directly into their body.
Because of this, Insect Breathing contained zero slashing motions. It was all about the fastest, simplest, and most lethal thrusts.
The Compound Eye Hexagon form sealed the enemy's escape routes with extreme speed while delivering multiple rapid stabs to flood the body with poison.
If her strength was the lowest among the Hashira, then her attack speed and frequency were the highest in the entire Demon Slayer Corps.
Shinobu's thrust was fast. Extremely fast.
So fast it left afterimages in the air, as if she had attacked six different spots at the exact same moment.
But—
To Shuya, a fully trained Nen user, it still looked too slow—even without using any Nen in his body.
"Sun Breathing, First Form… Dance!"
Shuya swung his plain white oak practice sword. His life energy instinctively clung to the blade in response to the special breathing rhythm.
He struck second, yet arrived first.
No fancy tricks. Just a simple, clean slash that completely neutralized Shinobu's attack.
"Insect Breathing… Butterfly Dance… Caprice!"
Seeing her fastest strike fail, Shinobu instantly adjusted her breathing and began fluttering around Shuya like a real butterfly.
She followed up with another lightning-fast five-stab combo.
"Sun Breathing, Second Form… Clear Blue Sky!"
Just like before, Shuya used the next Sun Breathing form. Though his execution was still clumsy, it perfectly blocked every one of her strikes.
"How strange," Shinobu thought as she flipped backward, using the recoil to land lightly on a tree branch like a butterfly.
She stared at Shuya, who was mechanically performing Sun Breathing forms. Something felt off.
His technique was obviously brand new and unpolished, yet he had blocked her attacks twice in a row—second but still first—and with exactly enough force to cancel her strikes without hurting her.
Was it a Blood Demon Art?
Or—
Was he using her as a training dummy on purpose?
Shinobu glanced at the other fight between Saeko and Giyu. The Water Hashira was being completely dominated, yet somehow he hadn't taken a single scratch.
Saeko was toying with him like a cat playing with a mouse, using the exact same Sun Breathing forms—only with far greater proficiency than Shuya.
This can't continue!
"Insect Breathing… Centipede Dance… Hundred-Legged Zigzag!"
Shinobu made up her mind and unleashed her strongest technique.
"Sun Breathing, Third Form… Raging Sun!"
Shuya's response was the same as always—straightforward, by-the-book execution of the next form.
He wasn't even paying attention to what specific technique Shinobu was using. He simply let Sun Breathing instinctively counter her attacks while focusing on something else:
The way his own life energy changed when he performed the forms.
He had discovered that when he used Sun Breathing, the special breathing rhythm caused his life energy to gather on the blade on its own—similar to the Nen technique Shu—strengthening the wooden sword.
The only problem was the massive drain on his life energy.
If his normal daily leakage of life energy was a 1, and the leakage when his pores were fully opened was 1,000, then using Sun Breathing forms burned at least 80 to 100 at a time.
No wonder every man in the Kamado family who inherited the Dance of the Fire God died young. Constantly using a technique that consumed life energy like this, with zero replenishment? Of course they'd have short lives.
After figuring that out, only one question remained.
Back in the Highschool of the Dead world, after more contracts, Shuya had learned exactly what the Nen seed did.
Normal contractors awakened Nen like regular users.
But those who signed after having their pores opened? Because of the foreign aura already inside them, their efficiency in their own type hit 100%, and their adjacent types reached a ridiculous 90%.
Then there was Rika, who had spent over a year struggling to awaken Nen the hard way. After contracting, not only was her Specialist efficiency 100%, but her adjacent types—Manipulation and Conjuration—also hit a perfect 100%.
So here was the real question:
If Breathing Techniques could achieve an alternative form of controlling life energy…
Could contracting a swordsman who had mastered a Breathing Style produce the same kind of insane efficiency boost as Rika?
Shuya was very curious.
He looked at Shinobu in the distance. "Is that all you've got? Is this the best a Hashira of the Demon Slayer Corps can do?"
"Hah… hah…"
A bead of sweat slid down Shinobu's forehead.
During the time Shuya had been lost in thought, she had already used every single Insect Breathing form she knew against him.
None of them had worked.
Every single attack had been casually blocked.
Worse, the constant offense had drained her stamina badly. She could barely maintain her breathing rhythm now.
The girl saw no path to victory.
The same was true on Giyu's side.
The situation was terrible for both of them.
They weren't just losing—they couldn't even run away.
Was Muzan really this strong?
"I'm not done yet, Mr. Demon," Shinobu forced out. "I will pierce your heart with this Nichirin Blade."
"Really?" Shuya answered calmly. "I'm looking forward to it."
But just as Shinobu prepared to attack again, Shuya spoke up once more with the same request:
"I was hoping to play with you a little longer, but it looks like we're out of time."
"So… can we make peace, Miss Kocho?"
"What?"
Shinobu was caught off guard for a second.
They were the ones being completely suppressed. Why was he suddenly talking about making peace?
Then she followed his gaze upward.
Only then did she notice the sky was beginning to brighten.
The clouds on the eastern horizon were already streaked with brilliant golden light.
Dawn was breaking.
The sun was about to rise.
For a demon, sunlight was far more lethal than any poison on her blade.
So… he was planning to run?
"Not a chance!"
A flash of joy crossed Shinobu's face.
Shuya shook his head with genuine regret. "Too bad."
The moment the words left his mouth, a brilliant ray of sunlight broke through the clouds and poured straight down onto him.
Shinobu froze, completely stunned.
The Demon King Muzan…
He was… committing suicide?!