These three really were easy to understand.
Yuko looked at their very different expressions and couldn't help mocking them inwardly.
Inosuke's face was impossible to read, but judging from the fist he was holding high in the air, he was clearly excited—thrilled, even.
Tanjiro was mostly just pleasantly surprised.
As for Zenitsu… he was even easier to read. His whole color palette had practically turned grayscale, and there probably wasn't a single part of him that was happy about this.
Yuko spoke softly, "Zenitsu, if you're unwilling, it's better not to force yourself."
Hearing this, Zenitsu's face lit up for a moment—but when he noticed Tanjiro's and Inosuke's excited expressions, struggle flashed across his face. In the end, he shook his head, looking like he was about to cry.
"…Never mind. I'll go with them."
His expression was a masterpiece of inner conflict—an actor-level performance.
Yuko couldn't help letting the corner of her mouth lift slightly.
If Zenitsu were alone, he probably wouldn't be this resolute. But after spending so much time with Tanjiro and Inosuke, the three of them had formed real bonds.
Even though he was terrified, he wouldn't leave Tanjiro and Inosuke to face danger alone.
Put simply, he was the type who complained nonstop while still helping anyway.
Annoying—but also strangely touching.
"Since everyone is so determined, I'll explain how the mark is awakened."
From her left palm, Yuko drew out a long, blood-soaked blade. With a casual flick of her wrist, she spun the sword, sending a spray of blood splattering across the ground like scattered plum blossoms. Beneath the blood, the blade's refined, snow-white surface gleamed.
Zenitsu shuddered involuntarily. He'd long known from Tanjiro that Miss Yuko was a demon, but seeing something this drenched in blood was still terrifying.
Miss Yuko was completely different from Nezuko. Just hearing Nezuko's voice made everything clear—but Miss Yuko's voice was frighteningly calm.
No—"calm" wasn't quite right. "Deathly still" fit better.
He'd always felt something was off, but since Yuko walked freely in daylight, Zenitsu had never considered that possibility. Who could've imagined she'd already overcome sunlight?
Yuko gave a simple explanation. "Awakening the mark is actually quite simple. You seek a breakthrough at the brink of life and death. As long as you break past your limit, the mark will naturally appear."
Zenitsu's voice trembled. "A-and if you don't break through?"
Yuko looked at him in confusion. "Then you die, of course."
"Noooo—!" Zenitsu screamed, grabbing Tanjiro and Inosuke. "H-hey, hey, let's go!"
Yuko laughed despite herself. "Just kidding. I'll judge your limits based on your physical condition. There won't be too much risk."
There was still risk, of course—but nothing compared to breaking through mid-battle against an Upper Rank demon.
Because Yuko would hold back.
They wouldn't.
"Don't joke like that! My legs aren't listening to me anymore!" Zenitsu's legs were already trembling.
Yuko kindly reminded him, "Zenitsu, if your legs are weak now, you won't be able to stand later."
Zenitsu screamed again, clutching the other two. "This is terrifying!!!"
Inosuke smacked him. "Idiot, let go!"
Tanjiro pried Zenitsu's hands off helplessly. "Zenitsu, stop messing around."
"But—!"
What a living comedy act.
Rengoku laughed loudly, hands on his hips. "Hahaha! You're all so passionate!"
He wasn't much different himself.
"In this fight, treat me as a demon. All you need to think about is cutting off my neck."
"I've already overcome sunlight, so you don't need to worry about Nichirin blades harming me. Even if you decapitate me, I won't die."
They had already reported the information about surviving decapitation to Ubuyashiki. Even he was troubled by it.
They had anticipated that Muzan wouldn't die from decapitation—but if even the Upper Moons could overcome that weakness, then things were far worse than expected.
Someone needed to restrain Muzan. Someone also needed to restrain the Upper Moons.
The Demon Slayer Corps' top-tier combat strength was starting to feel stretched thin.
Inosuke eagerly shook his Nichirin swords. "Is it time? I can't wait to awaken the mark!"
Seeing that everyone was ready, Yuko nodded slightly. "Yes."
Everyone placed their hands on their swords.
Yuko spoke calmly. "Then I'll apply a bit of pressure first."
Shinobu, watching from the veranda, brightened. Was it coming?
"Pressure?"
Before Tanjiro could fully process what Yuko meant, her crimson hair instantly turned white before their eyes. Her strange eyes shifted into golden vertical pupils, and two grotesque demon horns burst from her head. Fine blood vessels surfaced along her arms and cheeks.
So beautiful…
Light shimmered in Shinobu's violet eyes. What a breathtaking form.
Unlike Shinobu, who watched in silent admiration, none of those facing Yuko directly could smile.
Demon transformation?!
Tanjiro's breath caught as an overwhelming aura erupted outward from Yuko.
It was nothing like Akaza's fighting spirit.
Even before the battle began, cold sweat formed on Tanjiro's forehead.
If Akaza's aura merely made one's heart tremble, then Miss Yuko's felt like a heavy hammer slamming into his chest—breathing became difficult, and his arms began to shake uncontrollably.
What…?
His body was afraid?
The fight hadn't even started yet…
Tanjiro instinctively glanced to the side, his pupils tightening.
Rengoku-san's hands… were shaking too…
Everyone was afraid…
Suddenly, a noise sounded nearby. Everyone looked over instinctively—only to see the boar-headed boy already kneeling on the ground.
…?
Everyone stared.
Even Zenitsu, who was still shaking like a leaf, was standing. The loudest screamer had been the first to go down.
"Ugh… my body won't move…"
Yuko's expression shifted slightly. Was his heightened tactile sensitivity causing her aura to have the opposite effect on him?
She asked, "How is it? Can you adapt?"
Everyone felt deeply insulted—she was still asking if they were okay?!
That hurt.
The first to adapt to Yuko's overwhelming aura was the strongest among them: Rengoku Kyōjurō.
A grin spread across his face. "Miss Yuko really is strong."
"There's no need for compliments."
"No… there is." A streak of fiery orange-red light flashed as Rengoku burst forward, the first to reach her. He bent low, swinging his Nichirin blade upward toward her neck.
He'd listened to her instructions.
But—
Without even drawing her sword, Yuko slipped her fingers along the blade and pressed down firmly on the guard.
Rengoku's pupils shrank sharply. He instinctively tried to twist the blade free—
And then a calm voice reached his ears.
"You were just a bit short."
His body was already flying backward, completely out of control.