Although Shiro had cured Tanjuro and successfully averted the annihilation of the Kamado family, the long-term benefits of Tanjiro mastering the Sun Breathing style–just as he did in the original timeline–were self-evident.
Tanjiro was accustomed to heading down the mountain to the village every week to sell charcoal.
Neither Shiro nor Tanjuro could accompany him every single time; if Tanjiro could fluidly utilize the Sun Breathing technique, his own survival would be guaranteed by an order of magnitude.
More importantly, Shiro was desperate to glean the essential insights of the Transparent World from Tanjiro.
Unlike his father, Tanjuro, whose Transparent World was innate, Tanjiro’s ability was awakened through relentless, arduous training.
In the original story, Tanjiro had learned to perceive the “thin line” that signaled an enemy’s opening–a precursor to the Transparent World.
His hyper-sensitive olfactory powers surely played a role, but the experiential data Shiro could harvest from Tanjiro would undoubtedly surpass anything he could learn from his father.
“I understand, Shiro.
To protect my family, I will absolutely master the Hinokami Kagura as quickly as possible!” Tanjiro stared at Shiro with iron-clad resolve.
To him, his family was the singular most precious thing in existence.
Shiro merely offered a knowing smile.
In the original series, Tanjiro had undergone nearly two and a half years of borderline-self-destructive training under Sakonji Urokodaki just to achieve a rudimentary grasp of the breathing style.
Now, without any formal conditioning, the path for this Tanjiro to reach that same level was long and grueling, even with Shiro’s intervention.
Inside the house, Tanjuro had overheard their entire exchange.
He didn’t intervene, simply lifting his teacup and draining it in one long, contemplative swallow.
In an era plagued by creatures that defied humanity, having a powerhouse like Shiro–who seemed to exceed humanity himself–might actually be the key to finally ending the nightmare of demons once and for all.
Training began with ferocious intensity.
Because Shiro had spent the past month methodically sweeping the mountain and harvesting prey, selling furs in town meant the Kamado family was now living more comfortably than they ever had before.
“If you want to maintain the flow of Sun Breathing, your physical endurance must meet the standard.
Right now, your body is still far too fragile,” Shiro remarked casually, jogging effortlessly behind Tanjiro.
“Huff…
huff…
Yes, sir!”
Tanjiro breathed with ragged, desperate gasps.
His footsteps stumbled along the path as he struggled to keep the heavy sandbags strapped to his torso from sliding off.
Large, heavy beads of sweat cascaded down his face, and the steam rising from his head billowed into the frigid mountain air like wisps of fog.
Running from dawn until midday, Tanjiro had already completed several laps of the mountain while heavily weighted down.
For a twelve-year-old, it was an immense, near-impossible challenge.
“That’s enough.
Take a break and refuel,” Shiro commanded.
The moment the words left his lips, Tanjiro collapsed to the ground, his chest heaving violently as he gulped in the cold, crisp air.
Had his willpower not been forged of steel, he would have long since lost consciousness.
Shiro walked over with a satisfied expression, placing his hands onto Tanjiro’s back.
A faint, pale green luminescence shimmered into existence.
Under the influence of the healing Kaidō technique, Tanjiro felt as though his entire being were submerged in a soothing hot spring.
The deep-seated exhaustion from the training and the wear and tear on his muscles vanished in a heartbeat.
The intense contrast of comfort caused Tanjiro to let out an involuntary moan of relief.
“Shiro, what…
what is this?”
“It’s a specialized ability called Kaidō.
It treats physical trauma and simultaneously replenishes vital energy.” It was precisely because of this technique that Shiro dared to push Tanjiro into life-threatening, bone-crushing training regimes without fearing permanent damage.
If one followed Urokodaki’s methods without advanced restorative medicine, even without the side effects of the Demon Slayer Marks, the probability of Tanjiro living past fifty would have been slim.
Tanjiro instinctively flexed his arms.
Just as Shiro promised, every trace of soreness had been entirely erased.
Once Tanjiro was fully revitalized, Shiro withdrew the healing energy and helped him to his feet, pulling several massive food containers from a half-meter-tall backpack.
“Only by pairing this training with perfectly balanced nutrition can we effectively harden your muscles.
We didn’t have enough resources at home before; while you looked healthy, you were still significantly underweight.” Shiro popped the lids open, revealing a feast dominated by meat–essential for Tanjiro’s protein intake.
“But Shiro…
isn’t this way too much?” Tanjiro swallowed hard, staring at the mountain of food.
“Don’t worry.
I guarantee you’ll finish every bite.”
“It’s so delicious!
Did you make all this, Shiro?”
Watching the empty containers scattered across the grass, Tanjiro proved that the “Law of True Deliciousness” was a universal constant, regardless of the world.
“Mother and Nezuko helped with the preparations, too.
I couldn’t have whipped up this much food on my own in such a short window,” Shiro said, shaking his head as he sat atop a boulder.
“Your morning training is finished for now.
Next, I want you to attempt actual combat against a demon–though, just a very weak one.”
Tanjiro tilted his head, his eyes flickering with confusion.
*Weren’t demons only active at night?* The sun was currently at its absolute zenith.
“Arise, Death March.”
Tanjiro suddenly realized that a pitch-black *tachi* had appeared in Shiro’s hand.
It emitted a strange, pungent scent that the average person would find nauseating, forcing Tanjiro to cover his nose.
A swirling vortex of black spiritual particles materialized before him and dissipated instantly.
Tanjiro could swear he had never witnessed such a grotesque entity in his life.
Or rather, calling it a “living” entity was debatable; he couldn’t detect a single scent of life from it.
To him, it was essentially a mass of empty air.
“Don’t be afraid.
He might have been a man-eating demon once, but now he’s just a mindless puppet,” Shiro said, looking down from his position on the rock.
“I’m letting him act on his primal instincts alone.
This will give you a clear look at the insurmountable gap between you and a demon.”
Tanjiro was momentarily stunned.
Not only did this “younger brother” he’d picked up possess healing abilities, but he could also manipulate demons?
*Did I accidentally bring home a ‘deity’?* In Japan, legends of the eight million *kami* were woven into every aspect of life.
In certain worlds where gods walked the earth, throwing a brick in any direction risked hitting a minor deity.
The puppet, however, couldn’t care less what Tanjiro was thinking.
It let out a guttural, nonsensical roar, stretching its rubbery, elongated arms with lethal intent, aiming straight for Tanjiro’s throat.
Feeling the sudden rush of danger, Tanjiro’s skin crawled.
He dove to the ground, rolling across the dirt, narrowly evading the ugly creature’s strike by a hair’s breadth.
“This is…
a demon!”
Treating the threat as a matter of life and death, Tanjiro scrambled to pull an axe from the pack Shiro had brought along.