Three days had passed since Reinhard, Berche, and Saki had been officially welcomed as members of the Hourai Island Family.
It went without saying that each was enjoying their stay to the fullest.
Reinhard had completed the paddleboat he had long yearned to build, while Saki was busy expanding her knowledge regarding various materials.
Elsa, for her part, was accumulating experience by manufacturing magic tools Jin had encountered or created in the past—vacuum cleaners, refrigerators, lighters, popcorn makers, distillers, magi-lamps, and more.
As for Berche, who was neither a magi craftman nor an alchemist, she had taken to studying under Perido Leader of the Five-Colored Golem Maids. She spent her time learning various dishes and steadily increasing her culinary repertoire.
The attendant automata—Edgar, Ar, Neon, and Noir—weren't merely standing idle, either.
Edgar was being tutored by Laozi, Ar by Butler 1, and Neon by Soleil and Luna. Meanwhile, Noir was receiving various lessons from Land 1.
"Whew! Jin, the development environment here is absolute perfection!"
Reinhard spoke with sheer delight as he returned from testing his paddleboat at Tatsumi Bay. For the time being, he was relying on Marine 50 and 51 to operate the vessel.
"I don't think I could ever be satisfied with a common workshop again..." Reinhard muttered with a wry smile. Though he remained cooped up in the workshop all day, he seemed to be getting proper rest from evening through the night, usually because Berche dragged him away.
"Reiko-chan, could you... help me with something?"
It appeared Elsa was about to start a new project with Reiko. Lately, Reiko had been advising Elsa on various matters, and Elsa had come to rely on her quite a bit.
"Of course. What is it?"
"Um, I'm thinking of trying to make accessories this time, rather than magic tools..."
"I understand. You require assistance with the design, then?"
Through Laojun, Reiko had access to a wealth of information from across the world gathered by the Quinta. This included the latest design trends popular among noblewomen.
"Jin, I'd like a word with you, if you don't mind."
Saki viewed matters from a perspective entirely different from magi craftmen like Jin, which Jin found quite stimulating.
Saki was currently dressed in a white lab coat—a gift from Jin, crafted from fabric woven with ground spider silk. It was incredibly durable and naturally resistant to stains.
Between the coat and her glasses, she looked every bit the mad researcher. The look suited her far too well.
"What's on your mind?"
"Well, it's about Craft Magic. I was wondering... what exactly is Craft Magic?"
"Hm?...Well, I suppose it's the magic one uses for magi craft, isn't it?"
It was an utterly mundane answer, and it failed to satisfy Saki in the slightest.
"No, no, that's not what I'm asking. Hmm, let me rephrase the question."
Saki looked out through the crystal-glass window as she spoke.
"Magi craftmen like you, Elsa, and Reinhard can use the spell 'Forming,' correct?"
"Yeah, that's right. It's a staple of Craft Magic."
"And using Forming, you can process even adamantite, right?"
"Yes."
"Adamantite is the hardest metal known to man. Furthermore, it is non-interfering with regard to magic power. To be able to change its shape... must that not be a tremendously powerful spell?"
"I see where you're going with this..."
Jin understood the point Saki was trying to make.
Under normal circumstances, bending adamantite would require an astronomical amount of physical force. Yet, the Forming spell made it possible with a relatively small amount of magic power. Why was that?
"Hmm, I hadn't given it that much thought, but..."
Jin had formulated his own hypotheses about magic before. He decided to organize them in his mind once more to explain his view.
"It seems that Forming acts upon the atoms and molecules of a substance, weakening their bonding force before the shape is altered."
"I don't quite grasp those terms, but... are you saying it makes the material soft for a moment before changing its shape?"
While Saki didn't quite understand the specific concepts of atoms, molecules, or bonding forces, she seemed to have grasped the general idea.
"In that case, wouldn't Forming be one of the most powerful spells in existence? Swords, armor, even castle walls—if their shapes can be altered at will, they become useless, don't they?"
"Well, it's not quite that simple. First, the caster has to be touching the object with their hands. Second, the size of what can be processed is proportional to the caster's magic power."
"I see, I see. So, contact is a requirement, and the larger the target, the more magic power one needs."
"Exactly. Plus, it takes a bit of time to activate. You have to touch it, channel your magic, and then visualize the change. That process is a bit too slow for combat. It's not like firing off a quick fire spell."
With the exception of Jin himself, it was normally impossible for anyone to bend a sword mid-swing using Forming. Similarly, processing a castle wall to create a passage was generally impossible due to the sheer volume of magic power required.
"I see. I think I understand now. Thank you."
Conversations of this nature occurred frequently.
That had been the first day. On the second day:
"Jin, is it true that Craft Magic doesn't work on living organisms?"
This was another inquiry from Saki.
"Yes, that's right. For example, Shaping won't work on a standing tree. Even though you can cut it down with something like a Wind Cutter."
"Then at what point does Shaping become effective? Does it work as soon as it's been cut down?"
"Yeah, it does. Whether it's a branch or the trunk, once it's been separated from the living whole, you can process it with Shaping."
Hearing Jin's answer, Saki looked down in silent contemplation. After thinking for a full minute, she raised her head.
"I'll set aside the exact line between 'tree' and 'timber' for now....But in that case, what would be the reason Shaping doesn't work on the tree while it's still standing?"
It was Jin's turn to ponder. However, in less than thirty seconds, he hit upon a hypothesis.
"I suspect that Shaping—and Forming, which we talked about yesterday—acts upon free ether rather than mana."
Living beings in this world possess mana without exception. They take in free ether and convert it into mana within their bodies.
It seemed that mana circulated through living organisms. Jin presented his theory that as long as this circulating mana was present, Craft Magic would be ineffective.
"Oho! Incredible, Jin! That is a completely novel theory! In that case, one could even say that the requirement for becoming a magi engineer—or a magi craftman—is the capacity to manipulate free ether!"
And so the discussions continued.
On the third day, Saki came to him with a proposal.
"Jin, I've thought of a very interesting experiment. Would you be willing to help me?"
"What is it?"
Saki always came up with fascinating ideas. Expecting another one, Jin waited for her explanation with quiet anticipation.
"I was wondering if we might be able to melt ground spider silk."
"What!?"
Ground spider silk was peerlessly strong. However, while its thread-like form made it easy to use, its applications were limited to textiles.
"I see..."
Jin thought of nylon. More specifically, polyamide resin. One type, Nylon 66, was famous for being "stronger than steel and thinner than a spider's web."
Polyamide resins were used not only as fibers but also as structural plastics.
"You're wondering if it can be used as a natural resin. I hadn't thought of that."
Jin was immediately enthusiastic.
"Normal magic doesn't affect ground spider silk, right?"
Saki's question hit the mark. Ground spider silk would not burn or melt even under advanced-level fire magic.
"You mentioned that ground spiders consume free ether as food, didn't you? If so, couldn't one say that the ground spider itself is essentially a concentrated mass of free ether?"
That was something Jin had also suspected. Since they grew solely on a diet of free ether, their bodies were likely composed of the same substance.
"Father, Reiko told me once that Luna had previously investigated a dead ground spider."
At an opportune moment, Reiko provided a crucial piece of information.
"The lifespan of a ground spider is apparently quite long, but it seems one individual was crushed when its nesting hole collapsed. She brought it back to see if it could be used as material and analyzed it."
"A-And?! Go on, tell us the rest!" Saki pressed, leaning in eagerly.
Reiko remained unruffled by Saki's intensity and continued her explanation calmly.
"According to her report, eighty percent of its body was composed of free ether."
Persica on Hourai Island also contained high concentrations of free ether. It seemed the same held true for the ground spider.
"It might be accurate to say the silk is simply free ether that has changed its form," Jin remarked, and Saki nodded in agreement.
"The probability is high! The fact that it's immune to ordinary magic would certainly support that theory."
At this point, the two realized they had strayed slightly from the original topic. The goal was to melt the ground spider silk.
"Hehe, debating with Jin is just too much fun. I got a bit carried away."
"Right. We were going to melt the silk. Since we can bind the threads together with 'Fusion,' it should be possible. Reiko, could you bring me some ground spider silk? A scrap of fabric will do."
"Certainly, Father."
Reiko returned with a scrap left over from when Saki's lab coat had been tailored.
"Wait a second... Hmm, if I do this... alright. 'Dissolute.' 'Forming.'"
Saki nearly jumped in shock when she saw Jin spontaneously modify Fusion into an original spell, Dissolute. She managed to contain herself, however, as she watched the process of melting the silk.
The melted ground spider silk was translucent. Using Forming, Jin stretched it out into a thin, flat sheet.
"We did it, Jin!"
"Yeah, it worked perfectly."
Saki rejoiced at seeing her idea come to life, and Jin rejoiced at discovering a new potential for ground spider silk. The two of them were quite giddy with their success.
＊ ＊ ＊
Lastly, as a minor postscript:
"Jin-sama, I simply must have this restroom introduced to our home!"
"Jin, Jin! That toilet is a marvel! I want one installed the moment I return!"
The number of people obsessed with the Hourai toilets—which featured warm-water washing, deodorization, sterilization, and decomposition—had increased by exactly two.