The backstory concerning Jin and Deus Ex Machina's origins was finally settled.
"In that case, it would mean My Lord and Maquina are brothers."
"Right. Is there any problem with that?"
"No. However, since you have previously referred to yourselves as 'fellow disciples,' I wondered if people might question why you never mentioned being actual brothers from the start."
"That's a good point... Then again, we could just say we're distant relatives."
It was entirely plausible that two separate branches of a family had continued down through the generations until Jin and Maquina were the sole survivors of their respective lines.
"We might be distant relatives, but not brothers... Let's go with that."
"Understood."
In truth, it was doubtful anyone would pry that deeply into their lineage, but it never hurt to iron out every detail.
"Lastly, let's say Maquina is ten years older than me."
Being the exact same age would feel far too contrived.
"Understood."
"Well, now that I have some free time, why don't I go check on Avalon before heading to the Kingdom of Franz?"
Research and development on small aircraft was currently underway in Avalon.
Furthermore, Elsa had been somewhat concerned about Najas Kahn, the trainee doktor she had met back in the Kingdom of Franz.
At that moment, Elsa was working on something in the workshop.
"Hey, Elsa... What are you up to?"
"Ah, Jin-nii. Mm, spring clothes. I just finished."
It was an outfit tailored for Jin.
"Fashion trends are a little different from four hundred years ago. I tried making a modern jacket."
"Thank you."
First was the color.
People now favored slightly brighter tones than they had four hundred years ago, a trend that applied to both men and women.
While black remained standard for formal occasions, subtle accents of muted red or blue were incorporated to add an understated touch of elegance.
Next was the silhouette.
Loose, flowing garments had been the norm four hundred years ago, but form-fitting clothing was now in style.
Because the fit was so snug, poor tailoring immediately restricted movement, laying a tailor's true skill completely bare.
However...
"Ah, it fits like a glove, and it's really easy to move around in. Thanks, Elsa."
"You're welcome... It seems using stretchable fabric worked out well."
"Stretchable fabric?"
Jin indeed noticed that moving his elbows and shoulders felt remarkably effortless.
"Yes. I made thread by giving GST stretchability."
"That's impressive. You managed to give it elasticity without making it a knit fabric... How?"
"I twisted the raw filaments a lot."
GST possessed unparalleled tensile strength. Giving the fibers twenty times the normal twist produced a thread that functioned like an ultrafine spring.
She prepared strands with both right-handed and left-handed twists—the difference being the rotational direction during spinning.
Twisting these opposing strands together into a single yarn yielded a thread with forty to fifty percent stretchability.
"With about ten times the twist, the stretchability is around twenty percent."
"I see. So the twist is the secret."
"Mm, yes. Then I tailored the jacket from cloth woven with that thread."
Hearing that, Jin understood why the garment felt so comfortable despite its close fit.
"I'd expect nothing less from you, Elsa," he praised.
"Mm. Actually, Hanna-chan was the one who gave me the idea."
"Oh, really?"
Jin was thoroughly impressed, reminded once again of Hanna's remarkable brilliance.
"So, did you need something?"
Jolted back to the matter at hand by Elsa's question, Jin spoke up.
"Ah, right. I'm planning to visit Avalon soon, and I wanted to see if you'd like to come along."
"Mm, I'll go."
Her response came without a moment's hesitation.
"I thought you might. You're worried about Najas, aren't you?"
Elsa nodded at Jin's question.
"Mm. Plus, I'm curious about the current curriculum in Avalon."
"I see."
In that case, Jin suggested it might be best to prepare some relevant materials before leaving.
"Mm, let's do that... Laojun, do you have any suggestions?"
"Yes, Elsa-sama. What appears to be lacking in Avalon's medical courses are lectures concerning 'the structure of the human body.'"
An understanding of human anatomy was indispensable as foundational knowledge for healing.
Where specific organs were located and how they functioned; where muscles attached to the skeleton and what movements they controlled; how joints were articulated; where the major blood vessels ran...
Knowing these details beforehand allowed one to achieve the greatest possible efficacy when casting Healing.
With Laojun's assistance, Elsa set out to compile reference materials covering those essential topics.
"Now, what should I work on?"
Jin's primary objective this time was "small aircraft."
Currently, the only machines he owned that could be publicly demonstrated were the Eagle Unit 1 and the Delta X-02. However, the latter was still in its prototype phase, and Jin preferred not to reveal it just yet.
"In that case, the Eagle Unit 1 is the way to go."
He had already donated an identical craft to the Nord Federation, making it the safest and most sensible choice.
In shape, it resembled an inverted pot lid. It featured a circular wing, with a fuselage beneath the wing that doubled as a vertical stabilizer.
"Back then, I was pressed for time and could only manage the initial upgrade."
While keeping the circular wing design, Jin wanted to enhance its maneuverability.
"That means I need to rethink the fuselage."
Simply put, the fuselage was essentially a single flat plate.
While this structure helped improve straight-line stability, it came at the cost of turning performance.
"So, how should I tackle this...?"
After careful consideration, Jin concluded that allowing the fuselage to flex during turns would solve the problem.
More specifically, the rear half of the fuselage would not be rigidly fixed to the circular wing, allowing it to function as a rudder.
Because nearly half the fuselage could articulate, Jin reasoned that directional changes would become far smoother.
Of course, during straight flight, the configuration would remain unchanged, preserving its straight-line stability.
First and foremost, ensuring the structural integrity of the articulated fuselage was vital.
"Combining a truss structure with a honeycomb core should do it... Reiko, hold this in place for me."
"Yes, Father."
With Reiko assisting him, Jin set to work assembling a new Blow Plane based on the Eagle Unit 1.
Roughly two hours later...
The Eagle Unit 2 (Provisional Name) was completed before the day was out.
However, since night had already fallen, the test flight was postponed until the following morning.