Stripes!
In Demon Slayer, those who master breathing techniques to a high level can awaken the power of the Demon Slayer Mark—distinctive flame-like patterns on the body.
For an ordinary person, activating the mark requires a body temperature above 39°C and a heart rate exceeding 200 beats per minute. Once triggered, body temperature spikes—but so does physical ability, exponentially enhanced by the core effects of the breathing method.
Humans who awaken the mark are far stronger than those who haven't.
However, according to Demon Slayer lore, only Yoriichi Tsugikuni ever awakened the mark and lived past the age of 25.
The mark demands immense endurance. Only someone with Yoriichi's natural aptitude could withstand it without consequence.
But for Naruto?
His physical capabilities rival that of a Tyrannosaurus rex in human form.
No need to worry.
—
In the next moment, as Naruto practiced his breathing, flame-like markings emerged across his forehead.
The instant the mark appeared, he felt his heartbeat intensify.
Bang! Bang! Bang!
It thundered like war drums echoing across the battlefield.
A surge of power, like a raging river, roared through his limbs and bones.
Naruto immediately activated Kagura's Mind Eye and combined it with Observation Haki, scanning the changes within his body.
He noticed it right away—
His body was undergoing a remarkable transformation.
With the full breathing technique activated, along with the mark, every part of him—from his limbs to the tiniest cells—was gearing up for battle.
He felt fully armored from head to toe.
But that wasn't all.
Without warning, the power within his body began to resonate.
The flame-patterned mark stirred the hidden force within him—
Sage Mode.
Orange pigmentation bloomed around his eyes, its hue echoing the fiery pattern on his forehead.
As he entered Sage Mode, a flood of natural energy surged into his body, blending into potent senjutsu chakra.
Once again, Naruto's physical strength was pushed to a new extreme.
At this point, with Sage Mode, Breathing Technique, and the Demon Slayer Mark combined—
Naruto had no doubt.
If he threw a punch now…
Well, One Punch Man better watch out.
—
Then, Naruto recalled the Transparent World—a sensory realm only elite swordsmen could perceive in Demon Slayer.
It was said to be accessible only through relentless training and extreme pain.
Within the Transparent World, one's vision could pierce through flesh, revealing muscles, blood vessels, and even the rhythm of lungs.
The user could read an opponent's movement, predict attacks, and evade with flawless precision.
Through deep contemplation of the Transparent World and his own extensive knowledge of perception techniques—
Naruto had a sudden epiphany.
He understood the Transparent World.
No—he created his own version of it.
—
In that instant, his eyes shifted.
The world before him lost its veil.
But Naruto didn't stop there.
He fused the Transparent World with Kagura's Mind Eye and Observation Haki.
The result—
A sensory ability of ultimate insight.
His perception sharpened dramatically.
Now, Naruto could detect movement within a radius of dozens of kilometers. He could sense positions, numbers, strength levels—
Even emotions. Even inner thoughts.
Even the future, a few seconds ahead.
Most importantly—
With this Ultimate Mind's Eye, Naruto felt closer than ever to the realm of Da Luo Dongguan—the highest plane of enlightenment from cultivation lore.
—
Suddenly, Naruto turned toward the cage deep within his mind.
The Nine-Tails.
Kurama had been silently watching him.
But when Naruto's piercing sky-blue gaze fell upon him—
Kurama froze.
Their eyes met.
In that moment, Kurama felt as if Naruto could see straight through him.
Right to his soul.
Right to his… underwear?
Kurama blinked.
Then Naruto chuckled, and the familiar smile returned to his face.
Kurama let out a small sigh.
Damn it.
Why does this little brat keep getting scarier? I'm the freaking Nine-Tailed Fox!
Kurama grumbled internally.
But all he could do was mutter in his heart.
The great Nine-Tails, once feared by nations—
Now reduced to a tsundere fox with nothing but inner monologues.
Still putting on a tough front.
—
Time flew by like a shuriken in the wind.
Before they knew it, Naruto and his classmates were already more than halfway through their sixth year at the Ninja Academy.
Six years of growth. Six years of bonds.
And Naruto?
He was just getting started.
The Ninja Academy taught them the basic Three Techniques (Clone, Transformation, and Substitution), fundamentals of shuriken and kunai usage, intelligence gathering, wilderness survival, knowledge of the history and culture of Konohagakure, the shinobi code of conduct, and—most importantly—the Will of Fire.
As for Naruto himself…
After six full years of tireless training—
He had forged strength that now surpassed even the strongest shinobi in the village: the Hokage!
His state of mind and spiritual energy had reached a realm bordering on the mythical—almost touching that elusive harmony between man and nature.
His spirit had grown so powerful that it could resist the illusions of the Mangekyō Sharingan outright.
And then, there was the pinnacle of perception:
The Ultimate Mind's Eye—a fusion of Kagura's Mind's Eye, Observation Haki, and the Transparent World.
With this, he could sense an opponent's location, number, strength, emotions, and even their surface thoughts—sometimes even glimpsing several seconds into the future.
In terms of taijutsu:
Naruto possessed monstrous physical power, comparable to a tailed beast's might.
He had completely mastered the Six Powers (Rokushiki), pushing the human body to its absolute limit.
His hand-to-hand combat had reached the pinnacle, a result of countless years' worth of compressed experience and training.
He had even learned the combat technique of Shunshin Yoruichi—the master of speed—
And pushed it further, developing enhanced forms such as:
Shunraijū Battle Mode
Kyūbi Battle Form
And others.
In terms of breathing techniques:
He had learned seven:
Water Breathing
Wind Breathing
Thunder Breathing
Stone Breathing
Flame Breathing
Sun Breathing
Moon Breathing
He had also mastered the mysterious technique known as the Six Vaults Immortal Thief, allowing him to fight in a relaxed state and constantly evolve.
When it came to ninjutsu:
He had pushed the wind and fire chakra natures to their ultimate limits, achieving extreme elemental change.
He had mastered:
All known Fire Style (Katon) ninjutsu
Rasengan, Super Rasengan, Planetary Rasengan
Wind Style: Rasenshuriken, Super Rasenshuriken, and even Star Rasenshuriken
He also had access to:
The complete Hadō and Bakudō sequences (referencing the binding and destruction arts from Bleach, likely adapted into this world's logic)
Sage Mode, refined further through the Divine Mechanism: Hundredfold Object Manipulation
The technique known as Air Dance, granting mobility beyond normal human capabilities
Looking at the breadth of his current power, even Naruto was taken aback by how far he'd come.
He never imagined he'd become so strong.
But deep down, he knew…
It still wasn't enough—not for the crises that awaited him in the future.
He turned his thoughts to the Eight Unique Techniques he had set as milestones in his training journey.
So far, Naruto had already mastered some of them, and he was actively preparing for others.
But there were still three he had yet to touch:
Gathering Spirits and Drawing Rivers (Ju Ling Qian Jiang)
Twin Fist Technique (Shuang Quan Shou)
The Wind-Hou Qi Gate Formation (Feng Hou Qi Men)
...
TN:
Support me on P-com/LordMerlin