"Yamada-san, do we now possess the strength to kill Muzan?" Kyojuro stepped forward, his voice booming.
"Kill Muzan?"
Yamada looked at him and poured a bucket of cold water on his enthusiasm without mercy. "At your current level, if you encounter one of the top three Upper Ranks, you might be able to ensure you don't die, or perhaps even win by relying on numbers. But if you face Muzan directly, the swords in your hands are no different from sticks."
Upon hearing this, everyone's expressions changed.
"Why?" Sanemi frowned.
"With the enhancement of the Demon Slayer Mark, our speed and strength have multiplied several times over. Even if Muzan is strong, can our blades not even cut through his neck?"
"You can cut it." Yamada answered bluntly.
"But cutting it is useless."
Yamada reached out to Giyu. "Lend me your sword."
Giyu did not hesitate, he immediately drew his nichirin blade and handed it to Yamada with both hands.
Yamada gripped the hilt, his fingers brushing over the cold blade.
"The monsters in the top three Upper Ranks, including Muzan, have already broken through the limits of demons. A standard nichirin blade decapitation is not fatal to them. Muzan can heal the cut the instant your blade passes through his neck. Trying to kill him by cutting off his head simply won't work."
"Then what should we do?" Tengen's expression was grave.
If even decapitation was useless, then the experience summarized by demon slayers over the past thousand years would become a joke.
"If you want to stop their super-speed regeneration, you have to do something about your blades."
Yamada tightened his grip on the hilt. Suddenly, the muscles in his arm tensed slightly. An extremely pure, terrifying grip strength, devoid of any Chakra, clamped onto the hilt like a hydraulic press.
An astonishing scene unfolded.
Before everyone's eyes, the originally deep blue nichirin blade began to rapidly glow with a high-temperature, scorching crimson red, starting from the hilt.
The high temperature distorted the surrounding air. Even from several steps away, everyone could feel the scorching heat radiating from the blade, enough to completely incinerate demon cells.
"This... the sword turned red?!" Tanjiro's eyes widened.
"This is a bright red nichirin sword."
Yamada let go, and the crimson red on the blade quickly cooled, returning to its original deep blue. He tossed the sword back to Giyu.
"The material of a nichirin blade is scarlet ore that has absorbed sunlight. As long as your grip strength is strong enough, under extreme pressure, the blade will generate terrifying heat and transform. Demons struck by a Bright Red Nichirin Sword will have their wounds burned as if by the real sun, losing their ability to regenerate."
"But that kind of grip strength..."
Giyu looked at the sword in his hand. The sense of power Yamada radiated when holding the sword was simply inhuman. Even if he activated his Demon Slayer Mark, he could never exert the kind of force required to force steel to turn red.
"If you can't do it with one person's strength, then use a trick."
Yamada pointed to Sanemi and Giyu. "You two, activate your Demon Slayer Marks, use all your strength, and slam your blades together."
Sanemi and Giyu exchanged a glance, immediately understanding what Yamada meant. Since single-handed grip strength wasn't enough, they would use the extreme pressure and friction generated by the collision of two blades instead.
The two let out a low shout simultaneously, their Demon Slayer Marks appearing, and they gripped their swords with both hands, slashing fiercely at each other.
Clang!
A deafening sound of metal collision exploded.
Under the immense pressure, a cluster of dazzling sparks burst forth where the two nichirin blades met. Immediately after, that scorching crimson red rapidly spread along the collision point to the entire length of both blades.
"It worked!" Mitsuri covered her mouth in excitement.
Sanemi looked at the Bright Red Nichirin Sword in his hand, which was radiating astonishing heat, a flash of ecstasy in his eyes. With this, Muzan's super-speed regeneration would no longer be an insurmountable problem.
"Demon Slayer Mark, Bright Red Nichirin Sword."
Yamada stood with his hands in his pockets, watching this group of swordsmen who had finally reached the threshold of top-tier combat power, and continued, "There is one last thing. Transparent World."
"Discard your unnecessary killing intent, focus your attention to the extreme, and perceive your opponent's muscle contractions and blood flow. Only when you can close your eyes and see through an opponent's internal organ distribution as if it were a thin piece of paper, will you truly be qualified to stand before Muzan."
After explaining the final core trump card, Yamada turned around and walked toward Shinobu, who was waiting by the corridor.
Shinobu handed him a clean towel.
"Did you teach them everything?" She asked softly, handing him a cup of warm water.
"I taught them everything I could."
Yamada wiped his hands, took a sip of water, and cast his gaze toward the sky above the canyon, which was fragmented by the tree canopy.
"Next, it's just a matter of when Muzan decides to drag us into the game."
Just then, a Kasugai Crow flapped its wings, flying in hurriedly from outside the canyon, and landed straight on a wooden frame at the edge of the training ground.
"Caw! Urgent report! Urgent report!"
The Kasugai Crow's voice was hoarse and anxious, circling over the silent training ground.
"Message from Master! Multiple hidden strongholds across the country have simultaneously discovered a large number of mysterious eyeballs spying on them! Those eyeballs bear the character 'Four'! The Kakushi tried to clear them, but there are too many, it's impossible to kill them all! Caw!"
Hearing this news, all the Hashira instantly tightened their grips on their nichirin blades, their gazes turning in unison toward Yamada.
Muzan's surveillance had finally spread.
"A bit slower than I expected."
Yamada tossed the towel aside, a cold arc appearing at the corner of his lips.
He knew this was the final signal for the start of the decisive battle in the Infinity Castle. Once Muzan confirmed the specific location of the Demon Slayer Corps headquarters, he would definitely use Nakime's spatial Blood Demon Art to wipe everyone out at once.
"Everyone."
Yamada turned around. "The special training ends here. Go back, pack your weapons, and write your wills. Eat a full meal."
He took a step and walked toward the outside of the canyon.
"Prepare to go to hell and kill demons."