While the squad's training progressed smoothly, the puppet modification on Hiru's side had run into a wall. The appearance and aura had already been perfected, but the Zero-Type was still a combat puppet, and no one currently had the technical skill to fully replicate it.
Removing the six arms would compromise its structure, and even altering its programmed combat movements was an extremely difficult task.
Looking at the puppet now bearing Kagaya's face, Hiru covered his mouth again.
"No… I guess I'll have to remove the face after all. Seeing this face with six arms really makes me sick."
Goro carefully removed the puppet's face. Looking at the artificial eyes embedded in the mechanism, he felt that the puppet itself was far more unsettling.
[Hiru-san's sense of aesthetics really is… unique.]
Even so, having worked on prosthetics for so long and seen countless gruesome injuries, Goro remained calm.
Kotetsu, however, was another story.
Watching him deliberately avoid looking at the faceless puppet, Goro sighed quietly and returned to the mechanism manual Kotetsu had brought.
The puppet's construction was completely different from their own lineage. Their techniques relied on hidden wires and the user's muscle control to simulate natural movement. Without external power or exceptional control, their prosthetics were little more than lifelike decorations.
Kotetsu's puppet, however, was entirely mechanical. All controls were concentrated in the hands, allowing precise adjustments through a complex system of mechanisms, with up to a hundred preset patterns.
When Goro understood this, he couldn't help but sigh in admiration. If only he had been born in the Swordsmith Village, he might have witnessed such craftsmanship firsthand.
But that same level of sophistication was also why their research had stalled.
They couldn't risk dismantling it, fearing a single mistake might render it completely unusable. On top of that, the delayed activation of its mechanisms made precise control even harder.
"If we can't modify the mechanisms, then we'll have to hide them," Hiru said, staring at the six arms with clear discomfort. "Is there any way to conceal them? No matter how strange someone is, they wouldn't have six arms."
"But taking them apart could break the mechanisms," Kotetsu said, looking up. "This puppet is already hundreds of years old. Even a small adjustment could ruin it. Replacing the outer shell is fine, but we shouldn't touch the inside lightly."
"I think we still need to take it apart," Goro said calmly, closing the book. "Some damage is unavoidable. This puppet isn't meant to replicate a swordsman anymore—it's meant to imitate our master."
"The Zero-Type is designed for combat. Its movements are mostly offensive. Even with perfect timing, they won't work as they are. We'll need to redesign everything."
"For now, I can only replace the outer shell and some external parts. But after studying these materials further, I may find a way to modify it using our family's techniques."
He paused, then added:
"And the mouth needs adjustment too. A human face doesn't move like this."
Kotetsu lowered his head, gripping his shirt tightly.
"Do we really have to destroy it…?"
"To meet our needs, yes," Goro replied. "But before that, maybe it can serve one last purpose."
"One last purpose?"
Kotetsu blinked, then understood.
"But it's already so old… sparring with swordsmen could damage it."
"If it breaks, we'll deal with it then," Goro said calmly. "My grandfather always said that craftsmen face endless problems, but there are always more solutions than problems. And if it does break, it means the swordsmen are strong enough. That would make things easier for us."
"Making use of what we have…" Hiru smiled. "That's a good idea. What do you think, Kotetsu?"
"I do value this puppet," Kotetsu said, clenching his fist. "But you're all fighting for people like me. I want to help too. So… it's fine."
"Alright, let's go."
Hiru stood up and hoisted the faceless puppet.
"Goro, I'm counting on you."
"I'll study it carefully."
When they reached the training ground, Tanjiro had just knocked a swordsman to the ground. He immediately rushed over, helped him up, and brushed off the dust.
"Are you alright? I'm sorry—I thought you'd block that! I'm really sorry!"
The swordsman nodded stiffly.
"I'm fine…"
Honestly, it would've been better if Tanjiro hadn't said anything.
Watching him walk away, Tanjiro still looked worried. Just as he was about to call the next opponent, he caught Hiru's scent and turned with a bright smile.
"Hiru-san! You're here!"
Hiru waved and set the puppet down.
"I'm here to help relieve your stress."
Muichiro, having just defeated his opponent, ran over.
"Hiru-nii, are you here to help train too?"
"No, no. The puppet is."
Hiru patted the faceless figure.
"I have no intention of joining something this troublesome."
Kyojuro also approached, smiling brightly.
"A puppet for training? Excellent idea! I'd love to spar with the Zero-Type! Let me go first—facing a swordsman's style from the Sengoku Era would be a rare experience!"
Hiru sighed.
"Are you serious? With my brother here, why would you need a puppet?"
"…You're right!"
"Indeed."
Even Muichiro nodded.
"What?"
Kotetsu looked completely lost.
"Why wouldn't we need it if the Sun Hashira-sama is here?"
Hiru looked at him gently.
"Good kid… don't ask. Some things are better left unknown."