Riezel extended his hand again, this time reaching into Type Zero's neck and through its body.
Before long, he pulled a sword out from inside Type Zero.
It was an old sword housed in a worn-out scabbard, looking like it had quite a long history.
"What... What is that...?"
Kotetsu, who had been screaming, saw Riezel pull an old sword out from Type Zero's body, his eyes widening in shock.
"There's a sword inside the doll?" Tanjirou was equally surprised.
Clearly, no one had expected that a sword would be hidden inside Type Zero. Only Riezel, as if he already knew about the sword's existence, drew it out and nonchalantly reattached Type Zero's head.
In the next moment, Riezel reached out, placed his hand on Type Zero's chest, and used his magic, causing a dazzling magic circle to appear on his hand where it touched the Type Zero.
However, the magic circle flashed in and out quickly, appearing and disappearing so fast that Tanjirou and Kotetsu didn't even have time to react before it was gone.
Nodding his head, Riezel withdrew his hand.
"Alright, this should do it."
Riezel said as he returned to Kotetsu's side.
"Go check if it's fixed properly."
"…Alright." Kotetsu, with a blank expression, stepped forward.
His mind couldn't keep up with the rapid developments.
First, Riezel created a mechanical doll overnight that was better than his ancestor's doll. Then, there was actually a sword hidden inside Type Zero that he didn't know about. Finally, Riezel merely touched its chest and claimed to have fixed it.
Evidently, these incredible events had left Kotetsu's mind completely overwhelmed.
Now, he felt like nothing mattered anymore. Since it was all beyond his understanding, he might as well pretend he hadn't seen anything.
Only Tanjirou remained astonished by Riezel pulling a sword out of Type Zero.
"Big Brother... that sword is...?"
Tanjirou asked, looking utterly confused.
Riezel didn't immediately clear up Tanjirou's confusion but first raised the old sword and drew it from its scabbard.
In the next second, a rusty blade appeared before their eyes.
"This is Tsugikuni Yoriichi's sword."
Riezel held the rusty sword and said something that shocked Tanjirou and Kotetsu.
"Mr. Tsugikuni's sword...?" Tanjirou was shocked.
"There's no need to be so surprised. It's an easy deduction."
Riezel explained calmly upon seeing Tanjirou's expression.
"Yoriichi Type Zero was a mechanical doll made during the Sengoku period, so this sword must have been placed inside it during that time. Although the blade is rusty, you can still feel a faint trace of sunlight energy, proving it's a Nichirin Sword."
"Also, the blade of this Nichirin Sword has a faint black color, leaving no doubt that it's a black Nichirin Sword."
"In this case, a black Nichirin Sword preserved since the Sengoku period could only belong to Tsugikuni Yoriichi."
Riezel's explanation quickly overloaded Tanjirou's brain, but as the protagonist, he keenly noticed something important.
"Mr. Tsugikuni's Nichirin Sword is black?" Tanjirou asked in surprise. "Isn't a Nichirin Sword with a black blade something only people who are incompetent have?"
What he said was a small yet significant rumor within the Demon Slayer Corps.
Because Nichirin Swords reflect the breathing style suited to their wielder, anyone who obtained a Nichirin Sword immediately knew which direction to develop their skills.
However, there were two exceptions.
One was the people who couldn't change the color of their Nichirin Sword.
Nichirin Swords only reacted to swordsmen with a certain amount of skill. If someone who couldn't even master swordsmanship picked up a Nichirin Sword, it wouldn't change color.
In other words, those who couldn't change the color of their Nichirin Sword were recognized as novices and failures within the Demon Slayer Corps.
The other exception was those who made the blade of their Nichirin Sword turn black.
A Nichirin Sword with a black blade was extremely rare. Throughout the centuries-long history of the Demon Slayer Corps, only a handful of people had a black blade.
Furthermore, a black Nichirin Sword didn't correspond to any of the breathing styles passed down within the Demon Slayer Corps, leaving the wielder with no clear path to develop their skills. Because of this, wielders of black Nichirin Swords generally couldn't find the breathing style that best suited them, earning them the reputation of being incompetent.
Like Tanjirou, who used Water Breathing, which clearly didn't suit him while fighting Type Zero yesterday, causing his combat power to weaken and be affected to some extent.
Over time, some people within the Demon Slayer Corps started to believe that wielders of black Nichirin Swords were a bad omen, believing that they could never achieve greatness and that only the incompetent would wield such a Nichirin Sword.
Tanjirou had obviously heard this rumor.
Regarding this matter, Riezel only felt funny.
"Tsugikuni Yoriichi's Nichirin Sword indeed has a black blade. My Nichirin Sword is also the same." Riezel said with a faint smile. "Are you trying to say that both he and I are incompetent swordsmen?"
Upon hearing this question, Tanjirou immediately shook his head vigorously.
He couldn't afford to joke about that.
If such words got out, he would be drowned in spit.
Yoriichi was the founder of the breathing style, the greatest swordsman of the Sengoku period, and the most powerful swordsman in the history of the Demon Slayer Corps.
Riezel, on the other hand, not only could easily slay Upper Ranks and effortlessly crush all the Hashira but he was also seen as the hope to defeat Muzan.
If these two were considered incompetent, then every swordsman in the world would be trash, the most incompetent among incompetents.
"Although I can't be certain, I believe that those whose blades turn black are most suited for Sun Breathing."
Riezel continued his explanation.
"Tsugikuni Yoriichi's blade is black, my blade is black, and even yours, someone who's inherited Sun Breathing, is black. With all this evidence, the theory that swordsmen with black blades are most compatible with Sun Breathing is about eighty percent likely to be right."
"Moreover, since people like them are so rare, coupled with breathing styles in the Sengoku period not being as widespread as they are now, this sword likely passed down from the Sengoku period is the Nichirin Sword used by Tsugikuni Yoriichi."
Of course, that was what the original work also told, which was why Riezel spoke with such certainty.
"Kotetsu's ancestor had a close relationship with Tsugikuni Yoriichi. The fact that he could create a mechanical doll based on Tsugikuni Yoriichi proves he observed him up close and very carefully."
"For someone like him, getting Tsugikuni Yoriichi's Nichirin Sword isn't surprising. So, when he created Yoriichi Type Zero, he hid the sword inside it."
At this point, Riezel shrugged his shoulders.
"As for his intentions by doing that, who knows?"
Upon hearing the long explanation, Tanjirou looked at the old sword in Riezel's hand.
Obviously, the sword was rusty, making him doubt whether it could even cut through a leaf. However, after Riezel said that this was Yoriichi's Nichirin Sword, for some reason, Tanjirou suddenly grew fond of the sword before him. He felt that this sword seemed to be waiting for him to find it, and it had an inexplicable attraction to him.
*Ding—ling—*
Suddenly, the hanafuda earrings on Tanjirou's ears swayed and emitted a ringing sound.
After more than three hundred years, two items that once belonged to Yoriichi reunited at this moment.
Riezel held the old sword, looked at it for a moment, and then used his magic.
*Buzzz—*
Accompanied by a buzzing sound, magical energy flowed into the old sword, causing the rust on it to gradually disappear.
In no time, the old sword was no longer rusty but revealed its true sharpness, looking as if it had been newly forged—bright and pristine.
Needless to say, Riezel had restored Yoriichi's sword.
Following this, Riezel sheathed it and then tossed it to Tanjirou.
"Ehh?"
Tanjirou was first stunned, then hurriedly took the sword.
"It's something useful for you. Didn't I say you would find something useful before?" Riezel said with a smile.
His words quickly reminded Tanjirou of what he had said yesterday before they saw Type Zero.
Yesterday, Riezel had said to him that maybe he would find something useful here.
Was this sword the thing?
"Yeah, it's this sword."
Riezel continued as if reading Tanjirou's mind.
"Since your family inherited Tsugikuni Yoriichi's will, this sword naturally belongs in your hands."
"But... isn't this something you found, Big Brother?" Tanjirou quickly shook his head. "Besides, you also inherited Mr. Tsugikuni's Sun Breathing."
"I'm different from you." Riezel denied calmly. "Sun Breathing coming to me is more of a deal rather than an inheritance. The connection between me and him is nothing like your family's."
"But…" Tanjirou looked hesitant.
"I already have my own sword, which is much stronger than this sword. Even if you gave it to me, it would just gather dust." Riezel smiled slightly. "It's better if you use it."
Afterward, he turned his head to look in Kotetsu's direction.
"You don't mind, do you?"
"Just take it." Kotetsu glanced over and spoke indifferently. "I don't have the talent for swordsmithing since I'm not a swordsmith anyway. If you gave me that sword, I wouldn't even be able to polish it properly. Consider it the payment for repairing Yoriichi Type Zero."
As he said this, Kotetsu carefully touched Type Zero's exterior, checking its condition.
He had basically confirmed that it was truly repaired, and of course, the repair was perfect.
At this rate, Type Zero would last at least a few more decades.
Kotetsu felt satisfied with this and didn't care about Yoriichi's sword.
"Alright then..."
After hearing their words, Tanjirou finally nodded and accepted the sword.
Riezel turned his head to Type One following him, his smile widening.
'Hope this gives those demons a big surprise...'