No one told Tanjiro the answer, not even Tanjuro himself could provide it.
He only knew that Hinokami Kagura was passed down from his ancestors, and if he wished, he could dance it tirelessly all night.
He didn't understand the principles behind it, but Roy saw clearly through 'Gyo' —
It was Sun Breathing that gave Tanjuro his strength.
It helped him resist the cold and maintain his stamina.
It was just a pity that Tanjuro didn't know how to utilize this power, or perhaps... his frail body simply couldn't withstand its immense strength.
Even if Roy told him how to use it, he would die on the spot from the scorching heat of the Sun's power.
Once... twice... thrice... five times... six times... sleeves fluttering, kicking up snow, Tanjiro could no longer keep up and plopped down onto the ground.
On that night of heavy snowfall, only Tanjuro and Roy remained, dancing.
From initial clumsiness and awkwardness to barely managing, and then to seamless fluidity without a hint of stiffness, Roy danced more and more smoothly, eventually matching Tanjuro's rhythm.
Tanjuro noticed his movements, from his initial surprise to intentionally speeding up to test him, a smile unconsciously spreading across his lips bit by bit... A thought would occasionally pop into his mind: 'If Eiichiro's grandfather saw this, he would surely be astonished by his talent for learning Hinokami Kagura as well...'
Alas, the ancestors had passed away, Eiichiro's grandfather was destined not to see it... and Tanjuro already had a premonition that he too would soon depart... "Whoosh..."
A gust of wind blew, stirring Tanjuro's thoughts... Snowflakes fell through his mask onto Tanjuro's face.
The man was both relieved and melancholic, and when he came back to his senses, his heart was filled with guilt and regret... His mother was old and unable to work.
He had contracted tuberculosis years ago and couldn't do heavy labor.
In recent years, the family had welcomed several more children, and Kie couldn't leave them.
Now, the burden of the entire family would fall upon Roy.
But as a father, it seemed all he could do was pray... 'Then I shall pray earnestly...'
'I wish...'
'Lord Hinokami above, bless Eiichiro and the children with health and safety, free from illness and disaster...'
With a sweep of his long sleeves, Tanjuro danced earnestly, and it was only after the eighth repetition that he stopped.
A corner of his flame-patterned mask lifted, revealing his pale, sickly face.
Roy followed half a beat later, stopping with lingering enthusiasm, and with a supporting hand, helped Tanjuro back to his seat... Tanjuro patted his hand and sat down, leaning against the porch pillar.
The children cheered and swarmed around him, chattering incessantly.
Some praised how beautifully Tanjuro danced, some praised how amazing Roy was, and some teased Tanjiro for being as clumsy as a toad.
Tanjiro wasn't angry; he grabbed Takeo, who was teasing him, and tried to pull on the cowlick on his head, but Takeo dodged and hid behind Roy.
"Big Brother Eiichiro, it's just that Tanjiro is too clumsy!" Takeo yelled.
"Call him Big Brother Tanjiro."
Roy lightly tapped Takeo's little head with a chop, then gave him an amused glare, sat down, and began to recall the movements he had just performed.
One's own family knows their own affairs; children only see the superficial, not the truth.
Roy knew it wasn't that he was smarter than Tanjiro.
On the contrary, he had a head start: first, he could use 'Gyo' to analyze Tanjuro's movements more clearly than Tanjiro.
Second, thanks to the Zoldyck Family's hellish training, his physical strength far surpassed Tanjiro's, so it was naturally quicker for him to imitate.
Furthermore, Tanjiro was destined to learn Sun Breathing.
But he still needed to undergo the most crucial trial—withstanding the "Weight of the Sun"!
If he could withstand it, he would completely master Sun Breathing; if not, it would all be for naught.
The young man calmed his mind, neither sad nor joyful, and after finishing his recollection, he got up and went into the kitchen, returning shortly with two plates of dango... White rice wrapped in vinegar cloth and drizzled with sauce was the main course for tonight's Full Moon Festival.
Of course, there was also the miso soup Kie had served.
There was a piece of pork rib in the soup, so simple that Roy was a bit dazed... Since his birth in the Zoldyck Family, he seemed to have never eaten anything so humble; usually, not only was there plenty of meat and fish, but due to training, the family would also provide medicinal supplements.
Looking at Tanjuro's condition now, and then at the faces of Kie, Grandma, and the children... Roy deeply understood—
In an era plagued by demons, simply being alive was a luxury.
Moreover, in two years, apart from Tanjiro and Nezuko, all these vibrant faces before him would ultimately vanish.
This... was not what Roy wanted to see.
'To receive kindness is to ensure their future; since I learned Sun Breathing, I should give back.'
'At the very least, I should let them eat meat.'
Roy had a plan in mind, and as Kie smiled and announced dinner was ready... he clasped his hands together, picked up his bowl and chopsticks... and ate heartily under the night sky. Soon, the meal was over.
After helping Kie clean up and coaxing the younger ones to sleep, he took off his shoes and socks, found his futon, and lay down, shedding the day's fatigue.
By now, the night was deep, yet the snow made it as bright as day.
Roy, Tanjiro, Takeo, and Shigeru slept on a large communal futon.
Closing his eyes, he could still occasionally hear Takeo's teeth grinding and Shigeru's faint farts... Both the sounds and the smells were so real, so real that Roy began to wonder if, after this sleep, he would truly leave this place and return to the real world.
Beside him, Tanjiro tossed and turned like a salted fish, unable to sleep, eventually forced to open his large amber eyes and scoot closer to Roy, whispering, "Brother, are you asleep?"
"Brother" was Tanjiro's unique way of addressing him; the younger ones, including Nezuko, all called him "Big Brother Eiichiro."
Roy, with his eyes closed, lied, "I'm asleep."
Tanjiro: "..."
He let out an "Oh~," pulled the blanket over his face, and lay flat.
Roy knew what he wanted to say.
Tanjiro also knew Roy didn't want to talk right now.
Actually, what he didn't know was... Roy just hadn't thought of a suitable explanation yet.
Who knew that his Big Brother Eiichiro was also opening the Gate of Cognition and encountering this world for the first time?
'So, my foolish Otouto, please give me a little more time...'
'Just a little is all I need...'
Roy thought to himself, gradually falling silent.
He drifted into a dream.
Until—
"Woof!"
A familiar dog bark woke him.
The owner of the bark was Mike, the magical beast kept by the Zoldyck Family, primarily responsible for devouring humans who illegally trespassed on Zoldyck property and—for crowing.
That's right, at 3:50 AM, Roy woke up.
He sat up from the bed.
Seeing the grandfather clock in the corner of the room, and the familiar desk, wardrobe... he knew that he had left the Demon Slayer world and returned to the Zoldyck Family.