The next day, Jin decided to begin by crafting a communication magic tool.
He already understood the principles of transmitting information over long distances thanks to the Magic Eye and Magic Screen. Free mana—ether—filled the world, vibrating under specific conditions to transmit waves over great distances. It was remarkably similar to the way sound traveled through air.
Utilizing this concept, he developed a magic tool capable of exchanging audio. He dubbed it the manacam.
By combining the manacam with the Magic Eye and Magic Screen, he successfully created a mana-telecam.
"Perfect. If I install this, we’ll be able to maintain contact with the ground."
Next, he focused on safety features.
"I can adapt a barrier to negate physical impacts on the body."
His primary concern was ensuring no one would be injured even if the aircraft went down. A magic tool that generated a barrier to block physical blows was relatively simple to construct. He installed the device beneath the pilot's seat.
Then, he considered the possibility of an emergency evacuation.
The obvious solution was a parachute. Jin fashioned one out of ground spider silk, which was both incredibly light and durable. To supplement this, he added a further refinement.
"If I equip the user with a small Magi Jet Engine on their back, they can use it to slow their descent or change direction while parachuting."
Unlike the parachute itself, he wasn't certain how effective the engine would be for maneuvering, so he hoped the day to test it would never come.
With his safety measures complete, Jin began work on Prototype 2.
While the fundamentals remained the same as the first model, he refined the aerodynamics and reinforced high-stress areas with adamantite. Furthermore, he made it a two-seater, adding a dedicated seat for Reiko.
So far, everything was going smoothly. The real challenge was finding a way to prevent the engine from ingesting solid objects.
After agonizing over the problem for a while, Jin had a sudden flash of inspiration. He looked back at the physical defense barrier he had installed under the seat. In modern terms, it was a force field. Crucially, people inside it didn't suffocate, meaning air could still pass through.
"Wait... but it doesn't let air through if the wind speed exceeds a certain limit, right?"
The barrier successfully blocked high-velocity winds generated by magic, such as Wind or Wind Blow.
"Let’s see... right, this part of the magi-formula... I see. Here is where the threshold is defined."
Jin meticulously analyzed the magi-formula of the physical barrier. His expertise—the same skill he had used to evaluate Beena’s barrier-generating magic tool back in Blue Land—was on full display.
The result of his labor was a repulsive barrier applied to the air intake. It was designed to repel substances other than gases—meaning both liquids and solids. He also made it possible for the barrier to envelop the entire aircraft as a literal shield. Its only drawback was that wind-attribute magic could still pass through.
Finally, he ensured the craft could carry spare magi-crystals as a backup fuel source. Even if the ether converter malfunctioned, the pilot would still be able to perform a safe landing.
"That covers every safety precaution I can think of."
He recovered the control core that served as the navigation support system from the wreckage of Prototype 1 and copied its data. This ensured the new craft’s flight would be stable right from the start.
"Alright, let's go."
A little after noon, Prototype 2 soared into the skies above Hourai Island with Jin and Reiko on board.
"Wow, this really is a great feeling."
Actually soaring through the clouds for the first time, Jin was in seventh heaven. Reiko handled most of the actual piloting.
"Father, this vessel is much more stable than the last," she noted.
It seemed his intuitive adjustments to the aerodynamics had paid off.
"They say failure is the mother of success. I’d be in trouble if the new model didn't outperform the old one."
Jin then began practicing so he could fly the plane himself, with Reiko acting as his instructor.
"Please take it slow until you’re used to the controls."
Gradually, Reiko handed the controls over to Jin. By evening, he was capable of flying the aircraft on his own—though he knew this was largely thanks to the navigation support system.
"Ah, that was refreshing."
Jin was in high spirits after landing safely. Reiko looked equally pleased.
"I think I’ll have sweet dreams tonight."
With a light step, Jin headed back to the laboratory, where Soleil and Luna were waiting with dinner ready.
The following day, Jin decided it was finally time to build a boat of his own.
He settled on a trimaran hull. Like a catamaran, this three-hulled design was well-suited for high speeds. Moreover, since the engine and cabin could be placed in the central hull, he could maintain a low center of gravity.
He constructed the hull out of his now-preferred light silver. Then came the power plant.
"The engine will be... this!"
He had developed a Magi-Water Jet based on the design of the Magi Jet Engine. He had essentially replaced the wind magic with water magic, and the result was remarkably efficient. Since the principle was entirely different from a real-world water jet, the performance was peerless.
"I just need to make sure it doesn't suck in debris."
Applying the lesson he had learned from the bird strike accident, he installed a barrier to filter out solids like seaweed, ensuring the jet wouldn't clog.
After lunch, Jin and Reiko brought the boat down to Tatsumi Bay, with Soleil and Luna handling the transport.
"Alright, time for the maiden voyage."
Unlike a plane, a boat felt relatively safe. Jin took the helm and set off. Since he wasn't familiar with traditional nautical controls, he had rigged the system to function like a car. He used an accelerator to move; stepping on the brake deployed drag plates into the water, and a lever switched between forward and reverse. Steering was handled by a simple wheel.
"Oh, this is comfortable!"
The prototype craft glided effortlessly across the calm waters of Tatsumi Bay.
"Alright, let's see how fast she goes!"
Jin floored the accelerator. The trimaran surged forward, reaching a top speed of approximately seventy kilometers per hour.
"This is more than enough. Though I suppose Reiko is still faster," Jin muttered, glancing at his daughter in the passenger seat. Reiko smiled happily at the remark.
Having thoroughly enjoyed the boat—which, unlike the plane, had been a success on the first attempt—Jin returned to the port where Soleil and Luna were waiting.
"Right. I’ll name this first prototype 'Hydro 1'."
The name related to water, and for Jin, it was an unusually decent choice.
"In that case, the plane will be the 'Albatross'."
It was the name of a bird, but Jin simply liked the way the word sounded.
The next day.
"Now that the boat and plane are finished, it's time for mass production."
He intended to use the boats for the island's defense and the planes for defense, scouting, and mapping out the rest of the world.
"Reiko, have Soleil produce thirty planes and Luna produce thirty ships."
"Understood, Father."
Since they were simply replicating the prototypes Jin had already built, the task was easy for Soleil and Luna. It was worth noting that no ordinary golem in this world—nor even the most advanced ones—could perform such a feat.
Because he had no point of comparison, Jin didn't realize it, but only the technology of the Magi Craft Meister could produce such sophisticated golems and automata.
"While they do that, I'll create the golems to man the fleet. Reiko, I'll need your help."
"Yes, Father."
Jin prioritized lightness for these units, crafting them out of light silver as well. Having performed the process so many times, he finished forty golems without a single hitch.
As light silver was an isotope of titanium, its color could be altered by adjusting the oxide film on its surface. He designated the air-service golems as light blue and the sea-service golems as navy blue.
"Alright, everyone together now: Trans Info, Level 4....Good, I’ve really gotten the hang of this."
In the beginning, he had often accidentally transferred extraneous information or felt a heavy mental burden, but through repetition, he had mastered the technique. He could now transfer all necessary knowledge in a fraction of the time.
"I name you Sky 1 through Sky 20, and Marine 1 through Marine 20."
His naming sense, however, remained as functional as ever.
"Sky 1 and Marine 1 will serve as captains. You are now the Air Force and the Navy."
In terms of raw defense, Hourai Island hadn't improved much yet, as the units weren't equipped with weapons.
"Weapons... I don't really want to make them, but I suppose they're a necessity in this world."
With magical beasts roaming the wilds, Jin accepted that a self-defense force was a logical requirement.
"That aside, Sky 1, take your subordinates and scout the area surrounding Hourai Island. Create a map of our surroundings. I'll give you the specific instructions now."
Using Trans Info, he could impart the necessary procedures in an instant. In this regard, golems were far more efficient than humans, upon whom Trans Info didn't work.
Jin had long been curious about the island's exact location in this world, and he looked forward to finally seeing the results.
"Now then, I suppose I should think about weapons and armor."
Jin's creative drive showed no signs of slowing down.
"First, armor."
Hoping to find inspiration in his materials, Jin headed down to the warehouse in the laboratory's basement.