"Mr. Tetsumaru-yama, did you see that?" Chiba Yo asked Tetsumaru-yama. When he turned around, he found her standing there in a daze.
"Mr. Tetsumaru-yama?" Chiba Yo called to her in confusion.
"Thank you for letting me see a Bright Red Nichirin Blade with my own eyes..." Tetsumaru-yama came to her senses and spoke softly to Chiba Yo.
"A Bright Red Nichirin Blade?" Chiba Yo had never heard the term before and was puzzled.
"Most swordsmiths hope to see a Nichirin Blade turn red after they finish forging it. Do you know why?" Rather than explain the Bright Red Nichirin Blade right away, Tetsumaru-yama asked him a question first.
Chiba Yo shook his head. He had not even known that most swordsmiths hoped to see Nichirin Blades turn red.
"It all comes from a line in an ancient text preserved in the Swordsmith Village: 'The crimson blade known as the Bright Red Nichirin Blade can suppress demons' regeneration.'"
Before Chiba Yo could say anything, Tetsumaru-yama continued, "We swordsmiths pour our hearts and souls into forging Nichirin Blades so that you can slay demons and protect more people from harm.
"The most troublesome thing about demons is their ability to regenerate endlessly. Unless you cut off their heads with a Nichirin Blade or use sunlight, you cannot kill them.
"But that passage clearly states that a weapon called a 'Bright Red Nichirin Blade' can prevent demons from regenerating. If we could forge such weapons, you would have another advantage in your battles against demons.
"That is why the swordsmiths of the Swordsmith Village all hope to forge such a weapon. Yet that single line is the only record of the Bright Red Nichirin Blade. No one knows how to forge that crimson blade.
"After a long time spent trying and failing to forge the crimson blade described in the text, some swordsmiths suggested that a Bright Red Nichirin Blade was simply a Nichirin Blade that had turned red. After all, Nichirin Blades are the only weapons that can harm demons, and they can change color. It seemed a fairly plausible explanation.
"Once they accepted that idea, the swordsmiths began hoping the Nichirin Blades they forged would turn red. That would mean those blades might well be Bright Red Nichirin Blades, giving the Demon Slayer Corps swordsmen who wielded them a slight advantage against demons."
Tetsumaru-yama explained it all slowly to Chiba Yo. Usually impatient, she seemed remarkably composed now. As he listened, Chiba Yo began to feel respect for these swordsmiths.
They might not fight demons on the front lines, but it was because of them that the Demon Slayer Corps swordsmen could slay demons. They, too, fought demons and protected humanity in their own way.
Their hope that Nichirin Blades would turn red was really a hope that the Demon Slayer Corps swordsmen would survive their battles against demons. They cared about those swordsmen, too. Swordsmiths and swordsmen were comrades fighting on different battlefields.
"But that theory was soon disproved. Swordsmen who use Flame Breathing are very likely to turn their Nichirin Blades red, yet those blades cannot suppress demons' regeneration.
"Once they realized this, the swordsmiths began treating that passage in the ancient text as an unfounded legend. Still, because there was a chance it might be true, they continued hoping that the swordsmen wielding their Nichirin Blades could turn them red. After all, color was the only detail recorded about the Bright Red Nichirin Blade."
Tetsumaru-yama explained the reason to Chiba Yo, and he understood what she meant.
But Tetsumaru-yama was not finished. Looking at Chiba Yo, she continued, "When I saw you turn your black Nichirin Blade red just now, an idea came to me. That crimson blade had to be the Bright Red Nichirin Blade described in the ancient text.
"A Bright Red Nichirin Blade is a Nichirin Blade, but turning one into the other is not simply a matter of using your Breathing Style to make it red. Rather, the wielder uses some method to draw out the power of the sun contained within the blade.
"The raw materials used to forge Nichirin Blades are crimson red iron sand and scarlet crimson ore, mined from the mountain closest to the sun. Both are ores that absorb sunlight.
"That is why blades forged from them can harm demons. But the power of the sunlight absorbed by those ores over the years has never been fully unleashed.
"A Bright Red Nichirin Blade most likely draws out the power of the sunlight contained in those two ores. That is why it turns crimson and gains the ability to suppress demons' regeneration. After all, the sun is the demons' natural enemy."
How impressive...
Tetsumaru-yama's analysis left Chiba Yo a little awestruck. It also showed him how well she understood the ores and how accomplished a swordsmith she was. Otherwise, she could never have offered such an explanation.
"When I fought Lower Rank Two not long ago, it really couldn't regrow its limbs after I cut them off." Tetsumaru-yama's words reminded Chiba Yo of some details from that battle. Everyone said demons could regenerate quickly, but since joining the Demon Slayer Corps, he did not seem to have seen a demon regenerate.
Of course, that was partly because demons could not last more than a few exchanges against him.
Tetsumaru-yama was not surprised by Chiba Yo's words. She was very confident in her theory.
"Then if I can figure out what makes my Nichirin Blade turn red, the Demon Slayer Corps swordsmen could become even stronger!" Chiba Yo quickly realized this, growing excited.
"I'll start studying it right now!"
As he spoke, Chiba Yo took up his Nichirin Blade and prepared to experiment. Although he could turn it into a Bright Red Nichirin Blade, doing so was as simple to him as opening his mouth to eat or moving his legs to walk. He still did not know how it worked.
"Wait." Tetsumaru-yama stopped him.
Chiba Yo turned his head in confusion and saw Tetsumaru-yama holding out her hand.
"Give me the Nichirin Blade first. You can do that after I've engraved it. I still need to get back to the village before dark."
Tetsumaru-yama said this to Chiba Yo.
"All right. Sorry for the trouble." Understanding, Chiba Yo sheathed the Nichirin Blade and handed it to Tetsumaru-yama.
"Don't worry. I'll return it as soon as I can. I won't hold you up. If you really can figure out how to turn a Nichirin Blade into a Bright Red Nichirin Blade, it will be good news for all of us." Tetsumaru-yama accepted the blade and gave Chiba Yo her assurance.
Then she went to fetch her tools.
Before long, the Nichirin Blade was back in Chiba Yo's hands, now with the words "Destroyer of Demons" engraved on its blade.
"All done. My work is finished, and it's time for me to go. I hope you find a way to turn Nichirin Blades into Bright Red Nichirin Blades. Goodbye."
Tetsumaru-yama said this as she returned the Nichirin Blade to Chiba Yo.
She was quite satisfied with her visit to the Demon Slayer Corps Headquarters, and her opinion of Chiba Yo had improved considerably. While engraving his Nichirin Blade, she had found no chips or other damage. It was still as good as new, showing how much its wielder treasured it.
Although the swordsmiths knew it was perfectly normal for Nichirin Blades to suffer wear in battles against demons, seeing the product of her hard work remain intact still made her happy.
"Thank you for your kind wishes. Goodbye, Mr. Tetsumaru-yama."
Chiba Yo thanked Tetsumaru-yama and waved to her with a smile.
Tetsumaru-yama said nothing more. She put on her bamboo hat, turned, and left.
I should work hard to figure out how to turn a Nichirin Blade into a Bright Red Nichirin Blade, too...
After watching Tetsumaru-yama leave, Chiba Yo turned and headed toward the training grounds at the Demon Slayer Corps Headquarters.
Meanwhile, three boys set out on the road to Mount Natagumo...
Before you continue