Though Jin and Elsa were still weary, they had managed to recover somewhat, having left the most taxing social obligations to their Doppels.
They were currently relaxing in their guest suite at the Royal Palace.
"We managed to get through that somehow," Jin said.
"...Nn. All thanks to the Doppels and Laojun."
"Father, what are your plans for tomorrow?"
The voice belonged to Lotte. Tomorrow's schedule featured a luncheon referred to as the Post-festival.
"I hear it’s a buffet-style party, so I suppose it won't hurt to attend."
Jin felt a slight twinge of guilt for having slipped out on part of the earlier festivities. Since it seemed they would have a relaxing morning, they decided to go.
＊ ＊ ＊
"Jin, good morning!"
Prince Ernest III arrived at 9:00 AM. Only Lotte accompanied him today.
"Today, please teach me about golem muscles!"
"Sure, I can do that."
Jin found teaching the prince quite enjoyable. He felt that if the boy continued his studies this way, he could easily become a world-class magi craftsman. Yet, his royal status made such a path impossible. Jin couldn't help but reflect on how often a person’s talent and their station in life failed to align.
"Now, let's talk muscles." Jin shook off his idle thoughts and switched gears to the lesson.
"A muscle performs only one action: it contracts. By shortening, it pulls on the connected bone and bends the joint. It really is that simple."
"...That’s true."
"But because it’s so simple, it’s also incredibly deep. What is the contracting force? The range of contraction? The speed? And how fast does it respond to the command to 'contract'?"
Jin listed the various requirements for high-performance magical muscles.
"Secondary requirements include the operating temperature range—its resistance to heat and cold. Then there’s durability and shelf life."
"Whoa... muscles really are vital, aren't they?"
In a sense, the specifications required for muscles were even more demanding than those for the skeleton.
"As long as a skeleton is light and strong, it meets ninety percent of what you need. But muscles have so many different performance metrics to satisfy."
"Hmm..." Prince Ernest sank into thought.
"That said, thanks to the trial and error of those who came before us, we generally know which materials work best."
"Those would be materials from magical beasts," Jin explained.
"Commonly, we use magical beast hide. Now, a question for you. First, what exactly is a magical beast?"
"Eh? Um... I was taught it’s a general term for organisms that subsist on free ether," Ernest replied immediately, recovering quickly from the unexpected question.
"Right. And among those, the ones with particularly high physical strength are called magical beasts. There isn't a hard line between standard magical creatures and magical beasts... but that’s not the point right now."
Jin paused for a moment before continuing.
"Most magical beasts have incredibly tough skin—meaning their hide—to protect themselves. For many, that hide hardens when mana is passed through it."
Ernest listened intently.
"Furthermore, if skin developed wrinkles, it would become a weak point. Therefore, most hides are evolved to be extremely elastic."
"Ah, so that's why magical beast hide can contract!"
"Exactly."
Jin once again lamented the waste of Ernest's talent; the boy’s comprehension was truly exceptional.
"So, we start with the premise that magical beast hide contracts. Now, let’s think about how to improve that performance." Jin moved to the next step of the lecture.
"You can satisfy most requirements by choosing the right species. Ideally, you’d use something like a Sham Dragon."
While materials from dragon-types like the Sea Dragon were the absolute peak, they were far too rare to be practical, so Jin used the Sham Dragon as a high-end example.
"A Sham Dragon?! You only see one of those every few years... no, more like once every decade!"
It seemed even that example was still a bit too extravagant.
"It’s just an illustration. Last year, I heard several carcasses of Death Sea Serpents were harvested in the Kingdom of Elias. Those would be considered advanced-level materials."
Jin was the one responsible for that particular windfall, but he kept his face perfectly neutral.
"Other good options would be the sandworms from the Shouro Empire or the dragonic eels from the Klein Kingdom."
"Hmm, we don't really have magical beasts like that in our country."
Currently, the Kingdom of Egerea had to rely on imports for such materials.
"We'll set that issue aside for now. To summarize why we use hide, it eventually comes down to shelf life."
This was a major reason why the actual muscle tissue of magical beasts wasn't used directly. Whether it was due to their molecular composition or something else, there was a massive difference in how well hide preserved compared to raw meat.
"We can leave the 'why' to the alchemists. For now, just remember that hide contracts when specific mana is passed through it. Clear?"
"Yeah."
"But here’s the problem. When used as a muscle, you want it to contract only vertically. However, by its nature, hide tends to contract uniformly in all directions."
"Ah..."
"To fix this, a certain technique is used. Do you know it?"
"No, I haven't learned that yet."
"I see. Then I'll explain. The most basic method is to examine the hide for natural variations in contraction and orient the piece so the direction of greatest contraction runs along the length of the muscle."
That was the absolute baseline. However, the difference was usually only ten to twenty percent, which wasn't very effective on its own.
"If you stop there, the contraction might be insufficient. So, there’s another trick."
The trick was to stretch the hide in one direction during the tanning process. This way, the final contraction would be the sum of the 'pre-stretched' amount and the hide’s natural contraction.
"Heh, people really have thought of everything."
Jin reflected on how impressive his predecessors were for developing these techniques to meet the demands of magi-craft.
The previous Magi Craft Meister, Adriana Barbora Tsetse, had taken it even further by spinning the stretched hide into thin fibers and twisting them together, which improved flexibility and boosted contraction by another fifty percent. Jin kept that particular secret to himself for now. He had even experimented with combining different types of magi-fiber to mimic fast-twitch and slow-twitch human muscles.
"There's so much more to muscles than I thought!" Ernest looked genuinely impressed.
"I should probably head out now. Thank you, Jin!"
It was nearly 11:00 AM.
＊ ＊ ＊
"Jin-dono, Elsa-dono. The luncheon is about to start, so we've come to escort you."
Earl Kuzuma and his wife, Beena, arrived, using the formal tone required for their official capacities.
"Thank you. We're ready."
Today’s Post-festival was a relatively small affair. Jin and Elsa were able to attend without the overwhelming crowds of the previous days.
Despite the name, the Post-festival festivities didn't last until evening; they concluded with this meal.
The banquet was held in the inner garden of the Royal Palace. Round tables had been set out to symbolize equality regardless of status. Jin and Elsa sat at one table with Louis and Beena—the Count and Countess Kuzuma—and Kelichdore, the Minister of Magic.
At the adjacent table sat the Chancellor, the King and Queen, and Prince Ernest III.
After a light aperitif, a meal featuring plenty of vegetables and fish—tailored to Jin's tastes—was served.
"Lord of Kunlun, thank you for the magnificent commemorative gifts yesterday," the Chancellor called out from the next table. He was referring to the koban coins.
The Doppels, under Laojun’s direction, had distributed them to all the guests.
"To produce such exquisite work... you truly are a Magi Craft Meister," Minister of Magic Kelichdore added with a look of sincere admiration.
"Jin, you're leaving this evening, aren't you? I'm going to miss you," Ernest said.
"Now, Nest," the King said, gently rebuking his son for his lack of formality.
And so, the official wedding celebrations in the Kingdom of Egerea drew to a peaceful close.