Night fell, and the full moon hung high.
In the courtyard, the wisteria had long since withered. The evening wind rustled the dead branches and brushed the hair of the gathered youths.
"Nezuko, don't be afraid. Your big brother will protect you."
Tanjiro held his sister's hand. Nezuko had taken the medicine developed by Lady Tamayo and was turning human again, suffering fever and other discomforts—Tanjiro stayed by her side.
"I'll protect Nezuko too, so don't worry,"
Zenitsu interjected, his face ingratiating. But Nezuko didn't seem to mind, smiling and nodding.
Over the past two months, Tanjiro, Zenitsu, and Inosuke had joined the Hashira's training as successors, their skills improving rapidly.
They were already prodigies, and after Gusion's hellish training, they'd all mastered Total Concentration and even learned Demon God techniques—no weaker than the Hashira themselves.
Zenitsu had even gained some confidence, feeling ready to face the Upper Moons or even Muzan himself.
He was changed not just by strength, but by seeing the burdens his senpai bore.
Two months ago, he'd gotten the terrible news that his second senior, Kaigaku, died hunting demons, leaving no remains. It hit him hard, and through letters, he felt his grandfather's grief.
So Zenitsu wanted to slay demons for revenge and to show his strength, so his grandfather and Gusion wouldn't worry.
Most importantly, Gusion was always so busy—training the Hashira and the successors, hunting demons, using himself as bait against danger.
Zenitsu wanted to share the burden. He wanted to be strong enough to help, to even face the Twelve Kizuki and Muzan.
"The Hashira are all gathered—this really is an unusual night. I can smell a big battle coming,"
Inosuke, perched on the wall with his boar mask and twin blades, gazed at the stars.
"I wonder how Gusion-senpai is doing. With his speed, he should have returned by now if he'd finished the mission,"
Zenitsu said worriedly. They'd only heard after training that Gusion had gone out on a mission fifty kilometers away.
"Don't worry. Big Boss' really strong—there's no way he'd fall for the demons' tricks."
Camillia, who'd grown close to Tanjiro's group, was also on guard in the courtyard.
She and Whirlwind had completed Gusion's earlier mission, finding Kaigaku and… well, let's say Kaigaku ended up as dog food.
Afterward, Gusion kept his promise to keep them safe in the rear, away from demon hunting.
But hearing about Gusion's training, Camillia was moved. She knew that in the End Space, you had to keep improving, so she volunteered for training. Gusion taught her the Demon God technique, too.
She wasn't as talented as the Hashira, but she barely managed to learn it—a level 1 skill on her panel.
Even at level 1, she thought it was powerful. Learning it was Gusion's original creation made her respect him even more.
Before leaving today, Gusion had told her she could run if she wanted—there might be a big battle.
But she decided to stay. After spending two months with Tanjiro's group, she'd grown attached and didn't want to abandon them.
She figured Nezuko was vulnerable now, so even if she didn't fight, she could help by carrying Nezuko away if needed.
"Gusion-senpai said he doesn't like you calling him 'Boss'—isn't it a bit embarrassing?"
Zenitsu teased.
"He's the Big Boss,"
Chachahana replied, gazing at the moon. "Let's hope it's a peaceful night—and that Big Boss comes back soon and safe."
Just as she finished speaking, an explosion boomed outside the courtyard, along with the shouts of the Hashira.
Camillia's face fell—was she really so unlucky?
Zenitsu, with his acute hearing, reacted first. He leaped to shield Nezuko and Tanjiro, hand on his sword, eyes sharp:
"Tanjiro, stay with Nezuko. Inosuke and I will help!"
Inosuke, seeing the battle, jumped down without a word.
…
On the other side of the wall, the nine Hashira stood ready, watching as Muzan stepped from Infinity Castle.
Serpent Hashira, with keen senses, was first to spot the anomaly and alert the others—within two seconds, Muzan was surrounded.
"On such a beautiful night, seeing you eyesores really ruins my mood,"
Muzan said, adjusting his white hat. He was a stylish demon—after Nakime teleported him to safety, he'd even changed into fresh clothes.
"So this is… Kibutsuji Muzan!?"
Mitsuri exclaimed, never having seen a demon so ominous and powerful.
"Everyone's here. Looks like he's prepared and made his arrangements,"
Muzan thought calmly. In his view, Gusion and Yoriichi were rare exceptions—normally, Hashira were weak; he could slaughter them easily.
But seeing all nine Hashira together confirmed his intel: the Corps leader and sunlight-immune Nezuko were likely here.
The thought of eternal life and perfect sunlight immunity made Muzan grin; even the Hashira looked more pleasing to the eye.
He stretched out his hand and intoned,
"Blood Demon Art: Black Blood, Bramble Thorn."
In an instant, countless blood-red thorns spread from him. In Muzan's experience, this move could kill most Hashira.
If none of them were particularly strong, this would wipe them out—and then he could devour Nezuko.
He could already sense her delicious presence nearby.
But the next moment, as his thorns shattered, Muzan's smile froze.
Among the nine Hashira, a towering figure's aura surged—earthy-yellow markings appeared on his skin and face, like a wrathful deity.
He swung his meteor hammer, smashing the ground and shattering Muzan's thorns.
Then, pressing forward, he swung his hammer horizontally at Muzan with terrifying speed and force.
At the same time, the other eight Hashira moved, their auras surging; markings like tattoos spread across their bodies as they unleashed their ultimate moves.
Stone Breathing, Second Form: Upper Heavenly Smash!
Mist Breathing, Fourth Form: Sea of Clouds and Haze!
Water Breathing, Eleventh Form: Lull!
Sound Breathing, Fourth Form: Constant Resounding Slashes!
Insect Breathing, Dance of the Bee Sting: True Flutter!
Serpent Breathing, Fifth Form: Slithering Serpent!
Love Breathing, First Form: Smitten Strike!
Flame Breathing, Fourth Form: Blooming Flame Undulation!
Wind Breathing, Eighth Form: Primary Gale Slash!
Nine Hashira attacked in unison, their combined momentum overwhelming Muzan—clearly a rehearsed assault with coordinated attributes.
Flame and Wind Hashira's attacks amplified each other; Mist and Water created confusion; Sound Hashira cleared a path for Shinobu's poisonous thrust; Serpent and Love Hashira targeted Muzan's blind spots.
The display was a chaotic festival of color and light—a visual feast. Their attacks rained down, burying Muzan.
Boom—
In the blast, Muzan's Blood Demon Art was broken. With every direction blocked, he could only take the full force of the assault.
His head was smashed by the meteor hammer; his body was riddled with wounds.
In the chaos, the Hashira paused briefly to avoid friendly fire.
At that moment, Muzan's battered body suddenly leaped, escaping the encirclement.
But the Hashira didn't let him get away—the second wave of attacks crashed toward Muzan like a bombardment.
Dazed by the earlier onslaught, Muzan instinctively tried to flee, but in midair had nowhere to go—so he opened a portal to Infinity Castle.
As he rose, the door opened above, and he tumbled inside.
The portal closed quickly—the Hashira's attacks struck the door, shattering it, but the passage to Infinity Castle was already gone.
From Gusion's perspective, he saw a door open in the distance above Infinity Castle, moonlight shining in—a ragged form falling through.
The remaining demons and explorers inside were stunned, unsure what fell in.
No one could imagine that ragged lump was Muzan himself—the mighty Demon King, now beaten to tatters.
But as that bundle of flesh squirmed and reformed into a patchwork humanoid, Infinity Castle fell silent.
And Muzan's roar of impotent rage became all the more jarring:
"Demon Slayer Corps!!!"
His body barely stabilized, and Muzan was suddenly gripped by a sense of overwhelming danger.
He leaped instinctively, but was a split second too late—a jet-black blade slashed through, severing all three of his legs at the root!
"Gusion!"
Muzan roared in hatred. His legs regenerated almost instantly, but he didn't dare tangle with Gusion. As Kokushibo arrived and clashed with Gusion, Muzan quickly retreated, ordering Nakime:
"Keep them away from me—I need to go back again!"
With that, a door opened above him—again, leading to the Demon Slayer Corps headquarters courtyard.
As the door opened, he saw the nine Hashira turn to look at him. Muzan hesitated at the threshold.