Muzan stood in the dim Infinity Castle, his torn suit hanging loosely from his body as his true demon form was revealed. His crimson eyes burned with madness.
"Sol Mirek! Do you really think locking us in here is enough to stop us?"
Sol strolled forward calmly, hands still in his pockets, looking more amused than anything else.
"Oh? Then how exactly do you plan to get out?"
"Blood Demon Art, Black Blood Brambles!"
Countless black thorns burst from the ground and shot straight toward Sol. At the same time, Kokushibo's Moon Breathing slash cut through the air.
Sol did not even blink. He lifted one hand casually, and every attack froze in midair before turning into dust.
"This is impossible!" Muzan's pupils shrank violently. "I already have immunity to sunlight. My power should have…"
"Should have what?" Sol interrupted, his tone full of mockery. "Did you seriously think eating the blue spider lily would let you compete with me?"
Muzan's body trembled.
With a heavy thud, he dropped to his knees.
"Ancestor, we know we were wrong!" His voice shook with fear. He had believed that gaining immunity to sunlight would finally let him stand on equal ground with Sol. Now he realized how foolish that thought had been.
"We are willing to become your tools. We will work twice as hard from now on!"
Sol raised his hand, cutting him off.
"That useless act ends here."
His eyes suddenly turned cold, and an overwhelming pressure spread through the entire Infinity Castle. The space itself began to tremble. Cracks spread across the walls like spider webs.
"You think I cannot see through your little tricks?" Sol walked slowly toward Muzan, each step cracking the floor beneath his feet. "From the beginning, you have been planning how to betray me."
Muzan shook violently, his body covered in cold sweat.
"No, I would never dare…"
"Too noisy."
Sol waved his hand casually.
Muzan's body exploded into a cloud of blood.
"Watch carefully," Sol said as he turned toward the other Upper Rank demons. "This is what happens to anyone who defies me."
His figure vanished and reappeared in front of Kokushibo the next second. Upper Rank One did not even have time to draw his blade before Sol grabbed him by the throat and lifted him into the air.
"Moon Breathing?" Sol laughed quietly. With a slight squeeze of his other hand, Kokushibo's precious nichirin blade crumbled into dust. "Flashy, but useless."
He tossed Kokushibo aside like trash. The demon slammed into a distant pillar and collapsed.
Sol's eyes moved toward Doma.
"You seem to enjoy smiling a lot."
Doma's golden fan slipped from his hand and hit the ground.
"Ancestor, please spare…"
He never finished the sentence.
Sol threw a single punch. Doma's upper body disappeared instantly, leaving only his legs standing where he had been.
"Destructive Kill, Annihilation Style!"
Akaza charged forward with clenched teeth, his fist exploding toward Sol's face.
"No improvement at all," Sol said calmly.
He tilted his head slightly to avoid the punch and crushed Akaza's head with one hand.
Gyutaro and Daki huddled together, trembling. Gyokko stayed in a fighting stance but did not dare to move. Hantengu hid behind him, completely silent.
Sol looked around slowly.
"So? Does anyone else want to resist?"
The entire Infinity Castle fell into silence. Even breathing sounded loud.
Sol walked toward Muzan, who had just finished regenerating. Without hesitation, he stepped on his head.
"Remember this clearly. You are alive only because I find it amusing."
He pressed down slightly. The sound of cracking bones echoed through the castle.
Muzan screamed, but the sound came out broken and weak.
"Too loud." Sol kicked him across the floor.
"The blue spider lily is real. I did not add any tricks."
Muzan struggled to raise his head. A faint hope appeared in his eyes.
"But you are too weak," Sol continued calmly. "You are not even strong enough to make me serious, yet you dream of freedom under the sun?"
He turned toward the other demons.
"From today onward, the games are over. You will all become my training partners until I am satisfied."
The entire Infinity Castle became silent again.
Muzan slowly got up, his face covered in blood. His body trembled as he knelt, pressing his forehead against the floor.
"Ancestor is right. We understand our mistake."
As long as they were alive, there was still hope. Even if they had to endure ten years, a hundred years, or a thousand years, survival was still better than death.
The other Upper Rank demons also knelt. Doma's body slowly began to regenerate, but his fake smile was now twisted and unnatural. Kokushibo's six eyes remained tightly shut, his broken blade scattered on the ground. Akaza knelt silently, the markings on his body trembling.
Sol nodded slightly, satisfied.
"Remember today. Your only purpose now is to help me train."
"Yes, Ancestor," Muzan said hoarsely.
"Good."
Sol snapped his fingers. The space inside the Infinity Castle twisted again.
"Now let's begin today's training."
From that day on, the Infinity Castle became Sol's private training ground.
The demons rarely left it and slowly lost track of time. Only half a month ago did Sol finally allow them to leave for a short time each day after he took control of everything and gained the physique of a true demon.
After all, he wanted useful tools, not mindless corpses. If he pushed them too far, they would eventually break completely.
"Bang!"
Another heavy punch sent Muzan flying across the room. His body crashed hard against the wall before sliding down slowly. His suit had long since disappeared, and his entire body was covered in bruises and blood.
"Too slow," Sol said calmly, not even moving his feet. "Is this really the result of a month of training?"
Muzan struggled to stand, his eyes filled with fear.
"Ancestor, I…"
"Shut up."
Sol appeared in front of him instantly and drove a punch into his stomach.
"Continue."
On the other side, Kokushibo opened all six eyes at once. The moment he drew his blade, the temperature of the entire space seemed to drop.
"Moon Breathing, Tenth Form: Piercing Slash, Lunar Halo!"
Dark crescent blades filled the air and rushed toward Sol.
Sol did not dodge. He simply stood there and let the attacks hit him. Not even his clothes were damaged.
"Flashy," he said again.
He grabbed Kokushibo by the throat and lifted him into the air.
"Real strength comes from the basics. Understand?"
Kokushibo nodded with difficulty, fear filling all six of his eyes.
In a distant corner, Doma was trembling.
"Too terrifying… too terrifying…"
"What are you doing hiding there?"
Sol's voice suddenly sounded right beside him.
Doma froze. Slowly, he turned his head and saw Sol standing behind him with a faint smile.
"Ancestor, please spare me!"
He fell to his knees instantly.
Sol snorted.
"Get up. Continue training."
Scenes like this happened every day inside the Infinity Castle. Sol trained the demons in the most brutal way possible, and none of them dared to even think about resisting again.