Finding an effective application for Gigant Peeder carapace—that was the topic Saki was currently researching.
After all, they had a mountain of it stockpiled on Hourai Island.
In the past, they had defeated five massive specimens measuring roughly fifty meters long, and nearly all of their carapaces had been kept in storage.
On top of that, they had brought down another 129 slightly smaller specimens—though calling them small was purely relative, as each was still a full ten meters in length.
There was no difference in the quality of the carapaces themselves; only the thickness varied.
"I really wish we could put this to better use," Saki lamented.
Back when Jin developed the barrier bomb, he had compressed a Gigant Peeder's shell.
(In that case, we ended up with an isotropic material... but there was never any real use for it.)
It was hard, heavy, and difficult to work with. On top of that, as a molecularly compressed material, it fell short of adamantite, which was why he remembered shelving it indefinitely.
It seemed Saki was looking into ways to make it a practical, easy-to-use material without relying on molecular compression.
"Hey, Jin, could you give me a rundown on biological materials in general?"
Naturally, Saki possessed plenty of knowledge on the subject herself, but she figured that hearing it from Jin's perspective might bring to light details she had previously overlooked.
"Sure thing."
Jin readily agreed and began his explanation.
"Magi-craft doesn't take well to organic materials. What's more, when something is alive, almost no magi-craft works on it at all."
"Right, that makes sense."
Jin nodded and continued.
"The primary reason is that the free ether flowing through living organisms interferes with magical effects. However, once a piece is shed or detached from a living body, it becomes possible to process it with magi-craft."
"That really is quite mysterious when you think about it."
"Indeed. You can't just explain it away by saying 'because it's alive,' after all."
If the free ether flowing through a living organism interfering with magic was all there was to it, then using a Magi-Jammer should have allowed magi-craft to affect living targets as well. Yet it still proved completely useless.
A Magi-Jammer brought the free ether within a designated area under Domination to neutralize an opponent's magic. When using one crafted by Jin, all the free ether in its radius was forced to obey Jin's mana alone.
In other words, within the range of that Magi-Jammer, Jin was the only one capable of wielding magic.
Even so, deploying a Magi-Jammer against a living creature did not make magi-craft any more effective against it.
"Still, once material is stripped or shed from a living body, magi-craft starts to work on it."
"Kufu, that's a research topic for another day, then."
Deciding to set that puzzle aside for now, Jin moved on.
"How easily it can be processed with magi-craft depends heavily on the biological material in question. To be more specific, I suspect it varies based on how strong the original creature's mana was, along with how much residual mana lingers inside."
"Mm-hmm, very interesting."
"And so, the carapace of a Gigant Peeder probably can't be processed by any second-rate or lower magi craftsman."
"Wait, is it really that tough?"
"Yeah. In my experience, Gigant Peeder carapaces are exceptionally stubborn."
It was even harder to work with than Ancient Dragon hide, Jin noted.
"Though I did manage to make knives and shields out of it."
Jin added that it was entirely natural for Saki's curiosity to be piqued by such a substance.
"Hmm... now I'm even more intrigued."
Three hundred and fifty years ago, Saki had been swamped researching more commonly available materials, leaving the Gigant Peeder carapace on the back burner.
After all, having a surplus of it was a privilege exclusive to Hourai Island; it was a material virtually non-existent on the open market, so it made sense that it had been set aside.
"Going by my own sense of it, if we set the processing difficulty of Ground Spider resin at 1, sandworm hide is around 2, and Death Sea Serpent hide is also a 2. Ancient Dragon hide would be around 10."
"Huh, so that's how they compare."
Putting it into numerical terms helped Saki grasp the relative scale.
"However, a Gigant Peeder carapace sits around 200."
"Whaaat?!"
Saki stared in utter disbelief at a number that was literally orders of magnitude higher.
"That... certainly explains why you find it difficult to process....Or rather, who else besides you could even touch the stuff, Jin?"
"Reinhard, Elsa, Beena, Stearena. And maybe Marikka... I'd imagine."
"Those aren't just first-rate craftspeople; they're the absolute pinnacle."
"...I suppose they are."
Saki's brow furrowed in thought.
"Hmm. As much as I want to unravel that secret, I suppose finding a practical application for the material comes first..."
Since they had all the time in the world, Saki decided to tackle her immediate priorities first.
"In that case... I have an idea," Jin spoke up.
"I can't guarantee it'll work, but what if we first drain the mana from the carapace, crush it, bind it together using some medium, and then channel mana through it once more?"
In essence, it was the concept of FRP he had envisioned earlier.
Carbon fiber was often aligned in specific directions, such as in layers, whereas short glass fibers were typically dispersed uniformly throughout a matrix.
The proposal immediately caught Saki's interest.
"Mm-hmm, should we bind it with magi-resin? Ah, wait, Ground Spider resin might be even better!"
"Good thinking."
Ground Spider resin seemed far more receptive to Reinforce through mana, so they decided to run with it.
Once drained of its mana, the carapace could be crushed by hand without relying on magic.
If ground too finely, it would lose its structural value as fiber, so they settled on a coarse crush.
From there, all they needed to do was blend it evenly into the Ground Spider resin.
"I think I'll experiment with different compounding ratios and see how the properties change."
Saki seemed eager to run tests to determine the ideal formula.
"Yeah, that sounds like the right approach," Jin agreed.
"Kufu, Smith 99 and I can take it from here. Thanks for your help, Jin."
"I'm looking forward to the results. Best of luck."
Jin was genuinely excited to see how the experiment would turn out.
After concluding his discussion with Saki, Jin returned to the House.
"Ah, is it that late already?"
The clock on the wall read 4:30 PM.
Elsa was nowhere to be found in the House, likely immersed in her own work—the Healing and plant magic research she had mentioned earlier.
"...Guess I'll take a soak."
Jin decided a dip in the hot spring before dinner sounded perfect.
With Mini-Reiko perched on his shoulder, he headed into the bath.
"Ahhh, that's the stuff."
Jin sank into the steaming water and let out a long sigh. He could feel his mental fatigue washing away even faster than his physical tiredness.
"Father, allow me to wash your back," Mini-Reiko offered, though her diminutive hands looked incapable of reaching his shoulders.
...Or so he thought, right until she engaged her force generator, hovered in midair, and began scrubbing his back with practiced efficiency.
What was more, her modulation of strength was exquisite—an unmistakable trait inherited directly from the original Reiko.
"Thanks."
Jin expressed his gratitude, scooped up some warm water, and rinsed away the lather.
"I wonder what the real Reiko is up to right about now..." Jin murmured.
"Father, would you like a report?" Mini-Reiko asked.
Content to let the warm waters soothe him, Jin decided to listen to the report right then and there.