April 1st dawned.
After breakfast, Jin set to work immediately—but first, he explained the design to Rubina and Marikka.
"Essentially, it’s a Blow Floater in the shape of an airship. I plan to make it about half the size of the Konron 3... no, let's say half the size of the Hurricane."
The craft operated on the principle of using wind-attribute magic without recoil to keep its gas bags aloft. Since the gas bag only needed to occupy the upper half of the structure, the cabin could be tucked away inside it.
"In other words, it's a Blow Floater shaped like an elongated bread roll."
It would be twenty meters long and ten meters high.
"I intend to use transparent Ground Spider resin—GSP—for the gas bag. That way, we can ensure visibility even when looking upward."
The population of ground spiders beneath Hourai Island had exploded, and their production volume had reached staggering levels. When Jin had asked Laojun just how much they had in stock, the reply was telling.
"My Lord, you could use as much as you desire, and the supply would likely last for decades," the magi-brain had answered.
This was, of course, assuming Jin didn't do something ridiculous like trying to build a ten-kilometer-diameter sphere made entirely of GSP.
"I'll use Neo 64 light silver... no, let's call it Neo 64 titanium now. I'll construct the framework out of Neo 64 titanium and then apply the resin sheets."
Following Rubina's example from earlier, Jin intended to assemble the craft without the help of the Smith units. Reiko, however, was in a league of her own; she provided support by hauling materials and standing by to intervene the moment things became dangerous.
"Gravita!...There we go."
By using Gravity Magic to lighten the components, Jin made it possible to assemble the heavy framework by hand.
"Jin-sama, you have completely mastered our magic as well..." Marikka watched him with eyes full of reverence.
Rubina could use the magic too, but the scale of Jin’s power was incomparable. Since becoming a duplicate, the amount of mana Jin could manipulate had increased by orders of magnitude, and he had even begun to master some of the spells used by the Northern People.
"Now, Rubina, don't get lazy—let's make sure we build proper scaffolding, alright?"
"...Yes, sir."
Rubina had a habit of setting up only the bare minimum of scaffolding in her rush to finish a project. In the worst cases, she would try to work with no scaffolding at all.
"Safety first, remember? It would be foolish to get injured while doing the work you love, wouldn't it?"
"...I understand."
Throughout the process, Jin hammered the essential principles of large-scale construction into Rubina.
"I'll set up an autopilot mode, a manual mode, and specific level settings."
"Jin-sama, I understand 'auto' and 'manual,' but what do you mean by level settings?" Rubina asked, leaning in to watch Jin’s hands.
"Well, it's like this..."
Level 1 was for beginners. Stabilization via gyros and support from the auxiliary magi-brain were fully automated, with a maximum speed capped at 30 km/h.
Level 2 was for novices. Gyro stabilization and auxiliary magi-brain support were reduced to half of Level 1's intensity, and the maximum speed was capped at 50 km/h.
Level 3 was for intermediate users. Automatic stabilization was turned off. Support from the auxiliary magi-brain was limited to high-risk situations, such as low-altitude flight, high-speed maneuvers, or extreme banking. The maximum speed was capped at 100 km/h.
Level 4 was for advanced users. Every function was manual. The magi-brain only intervened in cases of imminent danger. There was no speed limit.
Level 5 removed all functional limiters entirely.
"Of course, it's also possible to manually adjust exactly which functions are active and to what degree," Jin added.
Essentially, it was a choice between presets and manual control.
"What an interesting control scheme! As expected of Jin-sama." Rubina was deeply impressed.
"And with that, half of it is done. Rubina, why don't you try finishing the rest?"
"Eh? Do you think I can do it?"
"You'll be fine. Have confidence."
Jin gave her a supportive pat on the back, promising to keep a close watch.
"Ugh... alright, I'll try!"
Once she committed herself, Rubina started slowly, but her pace quickened as she found her rhythm.
Good, looking good.
Watching from behind, Jin was pleased to see things progressing exactly as he had envisioned. Rubina's handling of the GSP sheets was quite remarkable; she stretched them tight without a single wrinkle. While slack could be corrected later, it was far better to get it right the first time.
"Finished!"
"Mm, that’s a passing grade."
"Yay!"
Beaming at Jin’s praise, Rubina wore a radiant smile.
"Now, install the Blow Engines."
"Ha... eh? When did you make those?"
While watching over Rubina’s work, Jin had managed to craft ten Blow Engines.
"Haa... you really are in a class of your own, Jin-sama."
Marikka joined them just then.
"Jin-sama, the cockpit section is ready."
"Oh, thank you."
Jin began installing the cockpit Marikka had built at the very front of the cabin. Though they had decided on a five-person capacity the day before, Jin had allocated enough extra cargo space that they could likely fit five more people if they were willing to squeeze.
"In that case, they'd need to use the force generators as well."
Jin continued by installing an emergency Warp Gate, various barrier generators, and a manacam.
"Jin-sama, I've finished installing the Blow Engines."
"Excellent, Rubina. Next are the propulsion system and the gyros. Let’s do those together. Marikka, help us too."
"Yes!" Marikka agreed enthusiastically.
Reiko’s expression darkened slightly at being sidelined, but Jin quickly gave her a task.
"Reiko, contact Laojun and have him send over fifty bottles of Persica juice."
"Yes!" she replied brightly, moving to carry out the order at once.
They installed a mana tank inside the cabin and stocked it with the Persica juice to serve as emergency rations and hydration.
"Now for the transparent sections of the cabin."
Taking a lesson from past failures, Jin used a three-layer structure consisting of transparent corundum, GSP, and cubic zirconia. He designed the seats to recline and upholstered them with breathable GSS.
"The only question is the armament..."
Since the Elder, No. 700672, was a non-combatant who likely detested violence, Jin decided to limit the defenses to a Magi-Jammer, an ether jammer, and a Paralyzer. As a final precaution, however, he added a thoughtful feature.
"I'll install a transporter so they can teleport back to the front of 'the House' in an emergency."
The transporter could send or recall targets based on a marker, and its greatest strength was that it could even transport the user themselves. Since it couldn't send anyone to a location without a marker, he made sure to set one at ‘the House’.
"There. Now all that's left is a pilot."
Jin crafted a single golem based on the template of the general-purpose assistant golem Hope, designing it to handle both piloting and maintenance.
"Phew..."
While Rubina and Marikka were busy refining the fine details of the airship, Jin had already completed the pilot golem.
"We’ll let them decide the names for the ship and the golem. But first, let's take it for a test flight."
As the creator, Jin was recognized by the systems as the Arch Master. He decided to conduct the pilot golem's field test and the airship's maiden flight simultaneously.
"Oh, it's flying! It's really flying!"
"It's remarkably stable."
"It's so rewarding to see something we built with our own hands working so perfectly."
Jin, Marikka, and Rubina watched with satisfied smiles as the airship-type Blow Floater soared through the clear blue sky.
"Father, the unit reports no abnormalities," Reiko informed him. She was monitoring the situation through her internal manacam. "All levels from 1 to 5 are functioning perfectly."
"Good. That's a success."
Finally, the entire group boarded the craft for one last check.
"The ride is quite smooth."
Jin had worried that the smaller size compared to the Hurricane might make the "sway" more frequent and uncomfortable, but his fears proved groundless.
And so, the airship for Elder No. 700672 was finally complete.