Chapter 18: Walking on Water × Stepping Across the Void
"Nii-san, we're going to Mount Sagiri… it's to learn how to slay demons, right?"
"I heard from Grandpa Takei that there are demons down in the valley… and people who specialize in hunting them. Those people must be on Mount Sagiri."
Takei Sakan was their father's old friend, once the owner of a clothing shop. Years ago, he had moved to Tokyo, and contact had long since been lost. Roy vaguely remembered a round-bellied man with a thick beard, always wearing a double-breasted vest.
"It's me who's going to learn. Not you."
Roy walked calmly with the basket on his back. To his left ran the river, the River of Forgetting. Following it westward would lead straight to the town at the foot of the mountain.
"Why not bring me along?" Tanjiro protested, breaking into a jog and throwing his arms out to block his brother's path. "Nii-san, you promised to train me! Are you going back on your word?"
I promised to train you. I never said I'd teach you the Breathing techniques.
Tanjiro's body was still far too frail. If he were thrown into the Zoldyck household, even Mike the watchdog wouldn't bother with him. At best, he was on par with the would-be butlers still struggling through the mansion's trials.
So, before even touching Breathing, Roy had decided to do what his own family had done to him: build a foundation with brutal efficiency.
"All right."
The foolish little brother didn't realize what was about to come. His eyes lit up as he hopped excitedly in place.
And then, the very next second—
His excitement shattered.
"Nii-san… you can't be serious."
To reach the town before 7 a.m. That was impossible! Selling coal normally took four whole hours of walking just to get there and back. Roy wanted them to cut that time in half? Tanjiro's mind reeled.
"Run."
Roy gave the answer without hesitation.
If walking wouldn't do, then they'd run. With baskets of coal strapped to their backs. Endurance, lungs, and body—there was no better training.
He rolled his ankle, loosening his joints, and without another word strode toward the rushing river.
"You run along the bank. I'll run on the water. By 7, we must be there."
"Run… on water?" Tanjiro gaped, certain he'd misheard.
But the moment he saw Roy leap into the river, his heart nearly stopped.
"Nii-san!" He shrieked, lunging forward to grab him.
"I don't want to train anymore! Forget it, just come back up!"
Tears welled in his eyes. For the first time, guilt crushed him—
It's my fault… if I hadn't begged Nii-san to train me, he wouldn't have done something so reckless!
Tanjiro was too kind. Too kind to strike down a demon even when it threatened his sister. Too kind, almost to his own ruin.
He's crying?
"Reminder," Roy's voice drifted back, maddeningly calm. "Crying still counts against your time."
"Huh?!"
Tanjiro froze. He blinked away tears, and then—
There Roy stood. Not drowning. Not sinking.
Standing upright on the water's surface.
"Water-Walking"—a minor technique recorded in Zigg's old notes, one of many exercises in altering Nen's form. By imagining the flow of aura as broad, webbed paddles beneath his soles, Roy mimicked a duck's steps across the river.
And it worked.
His long crimson hair whipped in the wind as he sprinted across the surface, leaving a fine, silver spray trailing in his wake.
"Nii-saaan! Wait for me!" Tanjiro howled, half-laughing, half-crying, stumbling after him. Tears streamed freely, drying in the cold wind as he pounded along the riverbank.
[System Alert: Nen Shape Manipulation unlocked.]
[Form +0.05… +0.05… +0.05…]
Where there was no wind, he made waves. Roy couldn't even tell if he was truly treading water or forcing the river to bend beneath him. But the system's response was proof enough.
According to the notes, there's also "Cliff-Walking" and "Fishing Without Hooks." All exercises in reshaping aura to break free from natural laws…
In other words—man conquers heaven.
His eyes sharpened. He shifted his stance and tried merging the technique with Silent Step.
Instantly, the water exploded with overlapping afterimages, as if he were gliding across glass. A startled flock of egrets burst skyward, scattering feathers across the dawn.
"Kyuu!"
Their cries faded, leaving drifting plumes as proof of his passage.
Tanjiro stumbled behind, gasping for breath yet unable to look away from the spectacle. His chest burned, but his heart blazed hotter.
I want to be just as cool as Nii-san…!
With a roar, he pushed himself harder, chasing the trail Roy left upon the water.
Through the thinning trees, the outline of the town emerged—rows of wooden houses pressed together, merchants' cries rising with the smell of smoke, and the braying of mules echoing against the morning air.
Not long after, they finally arrived.
Roy, with a light step across the rippling current, landed gracefully on the riverbank.
Behind him, Tanjiro collapsed like a dead dog.
The foolish little brother's chest rose and fell like a broken bellows, wheezing desperately. Just as he managed to lift his head, two rice dumplings dropped neatly into his hands.
"Eat something and rest a bit," Roy said calmly. No matter what, this was his own little brother. Even in a world that demanded harsh lessons, he couldn't treat him like a mule.
They took a short break before stepping into town.
Thanks to their father Tanjuro's wide circle of goodwill, the Kamado family was well-known here. They didn't even need to shout—their two baskets of coal sold out in no time.
Afterward, Roy stopped at the marketplace: two sets of clothes for Nezuko, a few candies for Takeo and Shigeru, and a toy rattle for baby Hanako. The hours slipped away, and before they knew it, afternoon had come.
That was when Tanjiro froze in front of a blacksmith's shop, unable to take another step.
"Nii-san… what if we spend a little money to buy you a proper blade?"
The image of Roy slaying Sato Takeichiro days ago was still vivid in his mind. Back then, if his brother had been wielding a sword instead of a hoe, everything would've gone far more smoothly—Tanjiro was sure of it.
But…
"Don't waste your time. Ordinary steel can't kill demons."
Roy had already learned the direction to Mount Sagiri from a trusted acquaintance. He glanced back at Tanjiro, who answered with a faint "Oh," then adjusted the basket on his back and hurried after him.
As they walked, Tanjiro brightened. "The lady selling mushrooms said if we climb over the southern ridge, we'll reach Mount Sagiri. There's even a shrine on the mountainside. We can stay there tonight."
Yes… a shrine.
A perfect lure for demons.
Roy narrowed his eyes, his senses sharpening. In the distance, faint on the wind, he could already smell it—
The thick, metallic stench of blood.