Renewal Taekwondo in Multiverse

Flashback~

The night Mori killed his first demon, he had been unaware that he was being watched. A lone black crow perched on a nearby tree, its dark eyes gleaming as it observed his movements. It watched as Mori swiftly took down the creature, using his raw strength and precise strikes to incapacitate it. Then, with quiet efficiency, ensuring that the morning sun would finish the job.

Once the demon was completely reduced to ash, the crow spread its wings and took flight. It soared through the night sky, heading toward an unknown location. Eventually, it landed in front of a man who sat in quiet contemplation, his pale face adorned with purplish-pink veins and markings.

The man listened attentively as the crow relayed its findings. A boy, the sibling of a Demon Slayer, had killed a demon on his own.

Kagaya Ubuyashiki smiled faintly, his serene voice barely above a whisper.

"Kanae will most likely take her siblings to the Butterfly Mansion and tell them about demons. When the time comes, ensure she is informed that I wish to meet them," he instructed.

The crow cawed in acknowledgment before taking flight once more.

Present~

Mori lay sprawled on the ground, panting heavily, his body drenched in sweat. His training session had finally come to an end, but his muscles screamed in protest. The sheer intensity of using martial arts with a ten-thousand-pound staff in his ear had pushed him to his absolute limits.

Finally catching his breath, he let out an exhausted yet satisfied sigh.

"Finally! I managed to remake Daewi Han's Reverse Blue Dragon," he muttered.

His expression twisted slightly as he recalled the process. The technique was incredibly complex. Daewi had used energy flow from countering attacks to perform the move, but Mori had discovered something odd—the direction of energy flow had to be completely reversed. Reversing one's energy felt like forcefully altering the flow of blood within the body for ten full seconds. The process had been agonizing, but he had done it.

Letting out a groan, he forced himself up and staggered toward the mansion to take a shower.

By the time he finished, Kanae and Shinobu had returned from their outing. Kanae's gentle voice broke the comfortable silence.

"Mori, go get ready. We're going to meet someone very important, and we must look presentable," she said softly.

The words "someone very important" immediately piqued Mori's curiosity.

"Someone important, huh… Kagaya Ubuyashiki? Most likely," Mori thought to himself. "The Hashira are important, but they wouldn't care much about appearance. But why would he want to meet us? Kanae said she's only at the Hinoe rank right now, and that shouldn't be enough to get his attention yet…"

Despite his inner musings, Mori kept his expression playful and carefree, scratching the back of his head with a wide grin.

"Sure, sis! I hope they have food, though!" he said, feigning innocence.

Ten minutes later, Mori and Shinobu were dressed in standard black Demon Slayer uniforms, while Kanae wore her signature butterfly-patterned haori.

"Since you're both ready, let's leave," Kanae said with a soft smile.

The journey took three long hours. By the time they arrived, the sun hung lower in the sky, casting warm hues across the landscape.

A towering wall and massive gate stood before them. Upon passing through, they found themselves in an expansive courtyard. The area was meticulously maintained, with a stone-paved pathway leading to a small traditional building surrounded by carefully placed rocks. The air carried the scent of fresh grass and incense.

As they walked closer, Mori noticed a shadowy figure kneeling behind a thin silk curtain.

Kanae approached the entrance and bowed deeply.

"Master Ubuyashiki, I have brought my siblings as you requested," she said softly before stepping aside.

Two small figures appeared next to the man, gently assisting him to his feet. As they guided him through the curtain, Mori got his first clear look at Kagaya Ubuyashiki, the leader of the Demon Slayer Corps.

His appearance was surprisingly healthier than what Mori had expected. However, the slow, deliberate way he moved made it clear that his vision was nearly gone.

"At least killing Muzan will rid him of the curse," Mori thought to himself.

Kagaya lowered himself onto the tatami mat, his posture composed and dignified. After a brief silence, his serene voice filled the space.

"Which one of you is Mori Jin?" he asked. His tone was calm and soothing, like a gentle lullaby.

Mori raised his hand with a cheerful smile.

"That's me! And you are, sir?" he asked, waving slightly.

Kagaya chuckled softly.

"I see. I believe you encountered a demon a few months ago, correct?"

Mori maintained a blank expression, but internally, he was reeling.

"How the hell did he find out? Kanae said it was her first time meeting him earlier, so she couldn't have told him… Did someone else see me?"

His gaze flickered toward the crow perched on Kagaya's shoulder, and his stomach dropped.

"FUCK! I forgot about the crows!" he screamed internally.

Externally, however, he kept up his act, scratching his head sheepishly.

"Yes, I did see a demon, but I ran away as soon as it started chasing me," he said with an innocent grin.

Kagaya remained silent for a moment before speaking again.

"Kanae, can you take your sister away? I would like to speak with your brother alone," he requested.

Kanae gave Mori a cautious glance before nodding and leading Shinobu away.

As soon as they were gone, Kagaya's soft expression turned serious.

"You killed that demon, didn't you?" he asked directly.

Mori feigned shock.

"What? No way! I'm only five years old, you know! There's no way I could've done that," he said dramatically.

Before he could say anything else, a shadow leaped toward him.

A blade sliced through the air, aiming directly at Mori's head.

Reacting instantly, Mori rolled to the side, narrowly avoiding the attack. His body instinctively shifted into his combat stance—Fist of the Black Turtle.

Standing before him was a young man covered in scars, two prominent ones running horizontally across his forehead and under his nose.

"Sanemi… Not sure if he's the Wind Hashira yet, but this is definitely a test," Mori realized. "He doesn't have as many scars as when Tanjiro first met him, either."

His thoughts were interrupted when Sanemi lunged forward.

"Fast!" Mori noted, Barely able to track his movements.

Sanemi swung his sword, but Mori twisted his body to the right, dodging just in time. He cocked his fist back, channeling his strength.

"Fist of the Black Turtle!"

Sanemi's instincts screamed at him. He quickly raised his sword to block, but the sheer force of Mori's punch shattered his guard.

Mori didn't stop. He followed up with his next move.

"Kick of the Phoenix!"

The impact sent Sanemi soaring into the air, struggling to regain his balance.

As he fell, Mori took his stance once more.

"Dance of the White Tiger!"

A relentless flurry of punches and kicks struck Sanemi's defenseless body. Mori prepared to unleash his final attack, but he hesitated when he saw that Sanemi's eyes had already rolled back.

His body hit the ground with a loud thud, unconscious.

Silence filled the courtyard.

Mori exhaled, shaking out his fists.

"I should really upgrade my Fiery Eyes to have X-Ray vision soon..." he muttered.