Seeing that Marikka wasn't ready to be of much help yet, Jin decided to grant the golems basic knowledge of Craft Magic as well. This was so they could perform maintenance on one another to keep themselves in good condition.
He started by waking the first completed unit. The Master-Slave Magic he used to establish the chain of command was the same system he employed in Kaina Village, targeting an unspecified majority of the All-Creation clan. Specifically, this method designated the nearby Marikka as the representative and targeted everyone within the clan whom she recognized. If a new member joined, they could be added to the system through an introduction from the clan.
"Ji-Jin-sama?"
"...Stay still. I'm going to establish the golem's chain of command now."
"Y-Yeth."
Marikka was still tripping over her words as usual, but Jin ignored it and used Trans Info and Master-Slave Magic.
"There we go. Wake up."
"YES."
The golem rose. Standing two meters tall, the machine was rugged and imposing.
"Kyaa!"
"Whoa!"
Seeing a golem that had been lying down suddenly stand up was apparently quite shocking for those witnessing it for the first time.
"Even knowing what to expect, it is impressive..." Ladeous murmured, seemingly overwhelmed by its majestic appearance.
While the Gospel clan possessed golems, the All-Creation clan did not. Servants like Netros and Lucas had been performing those roles instead.
"This is a golem meant primarily for agriculture. Shall we call them 'Agrii'?" The name was, of course, derived from "agriculture." "This one is Agrii 1."
"YES. I AM AGRII 1."
"It can speak...?"
"Yes. Now, I'm going to make nineteen more identical units. Agrii 1, help me."
"YES."
The basic Craft Magic knowledge Jin had granted wasn't just for show; with the golem's help, finishing the next four units took only an hour. Then, with Reiko and those five units assisting, he completed the remaining fifteen in another hour. Those watching were beyond words at his efficiency.
All-Creation and Sion had been watching out of curiosity, but they seemed to have truly realized once again just what kind of person had been looking after them.
"Th-th-thuper... It'th th-th-thuper, Jin-thama."
Marikka was still so nervous she couldn't stop stuttering. Jin watched her with a warm gaze.
"Marikka, you still seem unfamiliar with Craft Magic. I've given these Agrii units basic knowledge of it, so if you're ever in the mood, you should have them teach you various things."
"H-Hyeth. Th-thank you very m-muth."
Marikka remained awkward until the end. He heard later that she was younger than Sion, so her reaction was only natural.
Having finished Agrii 1 through 20, Jin—or rather, his Double—took a slightly late lunch and then immediately resumed work. After all, since the real Jin and Laojun took turns operating it, the Double could effectively remain active without any rest.
Next was the construction of the greenhouses.
"...The question is what to use instead of glass."
If they were near Kaina Village, there would be a source of muscovite nearby, but it didn't seem to be mined here. Instead, transparent zirconia (zirconium dioxide) was being mined in large quantities and processed into window panes and cups.
"This could become an export item..."
Since it was rarely found on the Lauren Continent where humans lived, he thought it would likely become a valuable trade good.
"I see. That would be wonderful then," Ladeous remarked.
Even without making glass specifically, it was fine as long as they had access to an inexpensive transparent material. Zirconia had a melting point of over 2,700 degrees Celsius and a Mohs hardness of 8 to 8.5. It also possessed high toughness, making it suitable for cut glass.
But for now, the priority was building the greenhouses. Jin had Rolona select a suitable location and, together with the Agrii units, constructed frames out of light silver. Then, they fitted the zirconia plates into the frames.
"Oh, so this is a greenhouse."
Jin completed three greenhouses, each measuring three meters by six meters. Ladeous and Rolona, who stepped inside, were impressed by the warmth.
"It certainly is warm. But wouldn't it get cold at night?"
As expected, Rolona was quick to catch on. Even in the All-Creation clan's houses, they apparently had structures that let in sunlight to provide warmth, though they weren't exactly greenhouses. That knowledge was likely an accumulation of their experience with the harsh climate.
"Yes, that's why we'll install heaters."
"Heaters, you say?"
Fortunately, this region was rich in free ether. He was able to build highly efficient heaters with a simple structure. However, the problem was the thermostat—the temperature control mechanism.
"I heard from All-Creation that you have magic tools that can sense temperature, right?"
"Yes, you mean the temperature indicators," Rolona answered, pointing to the wall of the workshop. "That's one of them."
There, mounted in a round wooden frame that looked like a hand mirror at first glance, was a semi-transparent plate. It reportedly turned red when it was hot and white when it was cold.
"I wonder what the mechanism is?"
Reiko checked it on behalf of Jin's Double. Reiko's analysis and deconstruction capabilities were superior.
"Is it the hide of a magical beast?"
"Close," Rolona replied. "It's the skin of a lizard called an icefield lizard."
Apparently, they were reddish-brown in the summer and turned white as camouflage in the winter.
"Hmm, that seems difficult to use."
Incorporating that into a magic tool seemed too complex, so Jin excluded it from his options.
"...In that case, I'll need a temperature sensor after all."
Besides thermometers, there are many things that serve as temperature benchmarks. Water freezes at 0 degrees Celsius and boils at 100 degrees (at one atmosphere), and metals have fixed melting points that aren't heavily affected by atmospheric pressure.
In Reiko's case, she used high-purity fire-attribute magi-crystals as sensors to detect temperature. Fire-attribute magi-crystals constantly emit a weak amount of mana, but they have the property of changing the amount emitted based on the temperature. This allows them to be used to detect temperature changes.
However, the output isn't fixed at exactly 0 degrees Celsius, so it is necessary to calibrate the sensors using reference temperatures. Furthermore, regarding the effect of purity, low purity results in poor reproducibility.
In Reiko's case, besides the freezing point of water (0°C) and the boiling point (100°C), she had also memorized Jin's preferred bath temperature of 43°C (he liked it hot) and his preferred tea temperature of 62°C (due to his cat tongue), for a total of four reference points.
Since high-purity magi-crystals were rare, they were difficult to use for general thermometers.
"Well, it's not like I'm making a ton of them, and the demon territory seems to have plenty of mineral resources."
Jin took out three fire-attribute magi-crystals with the highest purity available from those provided.
"I'll do this, and then... Write In."
"Jin, what's that?" Sion peered at Jin's hands and asked.
"It's a temperature sensor....And then this goes here. Write In."
He combined it with other magi-crystals to assemble the heaters. Once fitted into light silver casings, they were complete.
"Rolona-san, these heaters have the property of generating heat when it gets cold and stopping when it gets warm," Jin explained in simplified terms.
By now, Rolona, Ladeous, Marikka, All-Creation, and Sion had all realized that Jin was doing something extraordinary. They were half-impressed and half-dumbfounded.
"Ah, y-yes! So we just need to install these inside the greenhouses!"
"I see. Jin-dono, you've done this so that we can cultivate crops even in the winter."
Even so, Rolona and Ladeous understood Jin's intention and grasped the potential.
"This is just the start. If we increase the number of greenhouses..."
"Yes, we'll be able to eat fresh vegetables even in the winter."
"I'm looking forward to it!" Sion's face was also glowing.
"Next is to increase the amount of cultivated land," Jin added.
Since their labor force had increased with the addition of agricultural golems, this was the logical next step.
"Tomorrow, let's consider clearing more land."