On a certain afternoon, roughly ten days after Xavier and his men fought on the Salt road.

　　Aura was performing her duties in her office like always and was reading the doc.u.ment that the “small flying dragon” had just delivered from the fortress on the edge of the royal domain, making a deep sigh.

　　“…Fuh. I see, the son of Marquis Guzzle failed the subjugation. Well, at least he brought back the concrete information about the cause of the road’s disorder. That is an achievement in itself.”

　　Thinking that it had turned out a little bit troublesome, she craned her neck while remaining seated on her chair. The sunlight coming in from the windows let her loose, red hair s.h.i.+ne beautifully.

　　“Yes. It certainly is a bit too much for a hundred soldiers if their target was an coordinated pack of over fifty Pack Dragons, like the report said. I would say Xavier-dono made the right decision.”

　　“I know that.”

　　Aura kept her face facing forward while she replied to her secretary, standing at an angle behind her, with such short and blunt words.

　　She agreed with the opinion that Xavier had made the correct decision.

　　The Carpa Kingdom was still in the middle of replenis.h.i.+ng the losses from the previous war. A young man in perfect health was an important a.s.set, no matter if he was under her direct command or under some feudal lord.

　　The subjugation couldn’t be called a success when they got rid of the “Pack Dragons”, but lost half of the soldiers in doing so.

　　For that reason, the third son of Marquis Guzzle had made a rational and correct decision in spite of being a young commander on his first a.s.signment.

　　At least Aura wasn’t counting the “subjugation failure” against Xavier. However, due to her position, it was likewise a fact that she couldn’t openly appreciate his decision.

　　“Now the ‘Pack Dragon Subjugation’ mission switched from the Guzzle Family to General Puyol.”

　　Aura heaved a deep sigh.

　　One thousand elite royal soldiers lead by General Puyol were already on their way to the fortress under the pretext of “countryside training”.

　　It was even possible that they had arrived there already.

　　Either way, the initiative of this mission had s.h.i.+fted to General Puyol.

　　As Aura couldn’t leave the capital, she could only watch in silence how things developed.

　　“Well, whatever. We are talking about that man here. He will definitely resolve the matter in one way or another.”

　　His personality aside, General Puyol could be trusted when it came down to his military abilities.

　　It was a bit unfortunate for the Guzzle boy, who wanted to raise his reputation as the next feudal lord through this case, but the re-establishment of the Salt Road was an urgent matter. It would be Marquis Guzzle first and foremost, when it came to compensating the resulting loss from a delayed solution, so they had to put up with it, even when their objective wasn’t exactly met. However…

　　“It certainly is hard to imagine that General Puyol will fail. The problem is that he will try to use this achievement as a stepping stone to reach even further.”

　　The slender face of Secretary Fabio kept an inexpressiveness that raised the question if he actually was wearing a well-made mask, while he said that in an unemotional tone.

　　“…Well, on the other hand, it might actually be a good thing. At least he will not be present in the capital when the Prince and Princess from the Twin Kingdom visit.”

　　Aura’s tone, as she said that, sounded kind of forced in order to comfort herself.

　　* * *

　　In the past, when Zenjirou had still been in elementary school, he had watched the talk corner of a music show.

　　There a certain musician had answered a question about his pre-debut time when he still had been poor: “What was the toughest part-time job you have experienced back then?”

　　And that musician replied at once: “It was a.s.sembling air conditioning units.”

　　For the simple reason that a room, where an air conditioning was to be a.s.sembled, naturally had no prior air conditioning. And since the room required air conditioning, it was accordingly hot.

　　An arduous work in a room without air conditioning and when you were finally done, you headed straight to the next place. Needless to say, that place had no air conditioning either.

　　The part-time job was akin to penance as you move from one room without air condition to another all day long in the middle of summer in j.a.pan. The musician claimed the air conditioning a.s.sembling job as such and back then, Zenjirou sat in his living room with air conditioned and ate rice crackers while commenting “Ahaha, oh really” with a laugh.

　　So, why was he remembering something from more than ten years ago now? The answer was simple.

　　“d.a.m.n it. The sweat got into my eye! I can’t see the scale of the level!”

　　“Zenjirou-sama, are you alright?”

　　“Z- Zenjirou-sama, please watch your step!”

　　At the present time, Zenjirou was sweating all over as he tried to a.s.semble the “air conditioning” inside the inner palace, where it was so hot that he would rather spent his time in the midsummer of j.a.pan.

　　“…Good, I got the backboard done…!”

　　Some way or other, he managed to a.s.semble the back board of the air conditioning at the wall of the bedroom and he muttered that with an expression like he was already satisfied with having accomplished just that.

　　“Zenjirou-sama, here, a towel.”

　　“Oh, thanks.”

　　Zenjirou took a well-chilled towel from the tall waiting maid, standing at attention next to him, and wiped the sweat from his face.

　　“…Fuh, I feel alive again.”

　　In the stuffy bedroom, he had stood on a ladder, set against the wall, and done unfamiliar work. The expression “feel alive again” was by no means an exaggeration.

　　With the help of the waiting maids, who had steadied the ladder or held up the back board, he somehow had succeeded in attaching the metal back board, glowing in a silver light, to the three wooden supports in a straight line with long screws.

　　“I’ve gotta be grateful to the carpenters. And I did cause some troubles to Aura yesterday. I’ve to reciprocate the favour later on.”

　　Zenjirou looked up at the just-finished back board and uttered that.

　　Yesterday he had worked out a special permission for the carpenters to enter the inner palace in order to a.s.semble the air conditioning. They had set up the wooden supports at the wall of the bedroom. The supports were properly stabilized with cross-beams, so it wouldn’t collapse even when the heavy air conditioning unit was attached to it.

　　The wooden construct with diagonal beams looked rather ugly against the white marble wall, but there was nothing to be done about it.

　　There was no way he could screw into the marble wall. His original world may have anchor screws and electronic screwdrivers, but unfortunately Zenjirou hadn’t considered these peculiar tools when he got ready to move to another world.

　　Anyway, after he wiped the sweat off his face with the cold towel and heaved a sigh, Zenjirou noticed that the waiting maid were standing respectfully at attention around him and called out to them.

　　“You can help yourself to the chilled towels as well. Ah, drink plenty of water as well. I wouldn’t want you to suffer a heatstroke or dehydration.”

　　The waiting maids, too, had done a tough job as they had steadied the ladder from below and held up the back board while Zenjirou had fastened it in place.

　　Unless they cooled themselves a bit and drunk enough water, there was a serious chance that they would break down.

　　“Yes, thank you very much.”

　　“We will gladly take you up on the offer.”

　　The waiting maids, drenched in sweat on their cheeks or scalps, thanked him honestly and quickly moved over to the neighbouring room, where the refrigerator stood.

　　Left alone in the bedroom, Zenjirou spread the bundle of papers, which he had printed out from various homepages in j.a.pan and showed how to a.s.semble an air conditioning by yourself, on top of the bed and read through them again.

　　“Hmm, I mounted the back board even to the wall. Next up, I attach the device to it once to see if it holds. After that I lay the plumbing, power cable and drainage hose through the hole in the wall…”

　　By saying so, he s.h.i.+fted his gaze to the right of the back board, where a round hole gaped in the thick marble wall. It was obviously pointing a bit downward, so that the drain water wouldn’t flow back into the device.

　　“Still, I’ve gotta say, professionals sure know their stuff, regardless of worlds. The hole got the right size and slope. They worked exactly according to my instructions.”

　　He uttered his admiration as he gazed upon the hole to the right of the back board.

　　Their skill of opening a hole into the marble wall, which was thicker than his upper arm was long, accurately to his instructions without using any electronic tools was so impressive that he couldn’t help but be fascinated.

　　The first-rate stonemasons of the palace apparently used “Element Magic” of the earth kind. Before opening a hole in the wall, they “weakened the stone” with magic and afterwards they “strengthened the stone” with magic again. Still, it didn’t change the fact that they had done an incredible job.

　　Zenjirou turned over the towel as it had gotten lukewarm from wiping his face once and used the still cool inner part to wipe his face once more. Then he raised a voice to get himself back into spirit.

　　“Okay, first I’ll set-up the internal device. Then pipe the plumbing and stuff outbound. After that, I a.s.semble the external device! …The external device, hmm…”

　　The sun was blazing outside. He would have to do the same kind of labour he did just now, now out in the courtyard without any shade.

　　“…Haah.”

　　He glared at the sun s.h.i.+ning in from the open window and heaved a sighed.

　　* * *

　　Around the time Zenjirou was sweating bullets as he a.s.sembled the unfamiliar air conditioning in the garden under the spa.r.s.e shadow of the parasols held up by the waiting maids, Queen Aura finished her duties in her office and swung by the back yard of the royal palace.

　　Surrounded by soldiers, wearing white leather armour and carrying short spears, from all sides, Aura walked over the ground dotted with weed with unusual large steps for a woman.

　　Compared to the front yard, which was kind of the figurehead of the royal palace, or the courtyard, where sometimes parties for privileged guests were held, the back yard could only be described as “bleak”.

　　To make up for that, though, it was bigger than the other two combined.

　　The place was allocated to the work of the craftsmen serving in the royal palace.

　　The stonemasons cut their stones here and the carpenters roughly shaped their wood here. The blacksmiths repaired the weapons of the Palace Knights here and the leathersmiths mended the armours.

　　In a way, you could call it the “business district” of the royal palace.

　　The royal palace also accommodated large fields, countless wells and gra.s.sland for the livestock used for food. With that in mind, it was self-explanatory that the palace could function as a fortress that was able to withstand a siege if necessary.

　　That said, the flames of war fortunately had never reached the capital so far, not even in the previous war.

　　As the craftsmen noticed Aura with the guards following her, they stopped their hands from working for a moment and bowed shortly.

　　“Greetings. Just keep working.”

　　Aura called out to them briefly and walked past them.

　　The craftsmen in the royal palace were allowed to skip the greeting while they were working, even when faced with the Queen. It was surprisingly lenient in that aspect.

　　The place Aura headed to with fast steps while drawing the attention of the craftsmen, was a wooden shed newly built this year.

　　It stood besides the ca.n.a.l of the palace and although it was new here, it obviously got special treatment, seeing as it had a waterwheel attached to it.

　　A couple of men in dirty working clothes stood at attention in front of the shed, waiting for Aura’s arrival.

　　“Thank you for coming, Your Highness Aura.”

　　An old man, his hair and beard completely white, greeted her as their representative. His aged, but robust hands, sticking out from the long sleeves of his s.h.i.+rt, were rather gnarled, which distinguished him as a proficient artisan. But a trained eye could see that the muscles hidden behind his s.h.i.+rt had become too weak for him to be still in “active duty”.

　　As opposed to this, everyone standing behind him were young men in their mid- to late-twenties, who couldn’t conceal their nervousness and had stiffened up due to it.

　　Their bodies were still slightly built and their palms far from battered.

　　A retired, old “blacksmith” and still fledgling “blacksmith apprentices”.

　　Aura had gathered these craftsmen for the “gla.s.s manufacture”.

　　At this moment in time, it was quite unapparent whether this craft would yield any result or not, so it had been impossible to withdraw manpower from the current active generation.

　　In front of the attentively “gla.s.s manufacture team”, Aura threw out her chest largely and talked straightforward.

　　“Give me a report. I heard you produced some result?”

　　The aged blacksmith nodded short to her words.

　　“Yes, Your Highness. According to your instructions, we have

　　heated up a mixture of white sand, milled sh.e.l.ls and natural baking soda for five days and five nights at the highest possible temperature and somehow succeeded in melting it together into a fluid substance.

　　Then we entwined it around an iron rod and cooled it down by suspending it into ash. Please take a look at the result here.”

　　Saying so, the old blacksmith held out a long and narrow object to Aura with his gnarled hands.

　　“Good.”

　　Saying so, she jerked her chin and one of the soldiers, standing at attention by her side, took it from the aged blacksmith. After he frisked the object carefully and had confirmed that nothing was wrong with it, he handed it over to Aura.

　　She checked the presented object with her own hands and raised a voice.

　　“…Oho. Certainly.”

　　To be frank, the object resembled a “greenish obsidian”.

　　The surface was relatively smooth, it glittered and had an almost pitch-black colour, so that you wouldn’t notice the green tint unless someone pointed it out.

　　By no means did it look like the “gla.s.s” that was used for Zenjirou’s tableware or alcohol bottles.

　　However, it definitely had a faint transparency when you held it up against the sun. As proof, its shadow, cast onto the hand, in particular was greenish, instead of black.

　　“Good.”

　　Seeing that shadow, Aura showed a satisfied smile and nodded.

　　It was nothing more than a drab pebble without any utility, but at least it proved that the method to create gla.s.s, taken from Zenjirou’s DVD, wasn’t mistaken in principle.

　　Definitely a success for a first try.

　　“Well done. Continue to specify the manufacturing process of this substance and try to find a method to increase its transparency. I know it is a completely unexplored field of work. You have all the time you need. Failures will be tolerated, too. But giving up on it is not an option. Give it your all from now on as well.”

　　“Yes! Very well!”

　　Upon her speech, the old blacksmith lowered his head excessively with these words. The rigid young apprentices behind him quickly followed his lead a second later.

　　Aura had actually spoken the truth. From the beginning, she herself had never expected that they would create the same gla.s.s that she had seen on Zenjirou’s DVD.

　　It was already “more than she could ask for” that they somehow or other made something that “certainly looked like gla.s.s on a closer look” in such a short time.

　　As a matter of fact, she had heard from Zenjirou that gla.s.s was even harder to melt than iron, so she had expected that it would still take some time before it took shape.

　　“So, how is it going? Right now, you are using a furnace for wrought iron as it is, it seems, but will it suffice in the future?”

　　The aged blacksmith shook his head with a bitter expression in response to her question.

　　“Not quite, Your Highness. I believe it to be somewhat problematic. To be honest, it would not be all that strange for the furnace to blow up in our faces at some point from the heat when we continue to repeat the current method. Besides, it takes us five whole days to refine an amount of just this size, so it will prove to be difficult to polish the technique.”

　　“Hmm… It ultimately might be quicker to advance the manufacture of the so-called “firebricks” at the same time… You are probably understaffed then.”

　　In a moment of silence, Aura placed her right hand against her chin and was absorbed in thought. And then,

　　“Okay. I will see what I can do to increase the personnel. But it will not happen right away. Continue your efforts with the current staff for now.

　　I leave it up to your decision whether you keep up with the research of ‘making gla.s.s’ itself or rather prioritize the research of the ‘firebricks’. Do the best possible. Understood?”

　　After saying so, she gave the elder blacksmith a questioning look.

　　“Understood, Your Highness.”

　　The former blacksmith humbly accepted the order of the Queen.

　　With her guards still in tow, Aura left the gla.s.s manufacture research shed behind her and walked along the ca.n.a.l towards a different area.

　　Before long, her eyes beheld a somewhat strange spectacle.

　　Namely, a great number of “waterwheels” set up parallel to the ca.n.a.l. In total, there stood ten of them in a line.

　　The common practice would consider it improbable.

　　If waterwheels were built one after another in such a short range, the hydraulic power would be too weak and the later wheels wouldn’t produce a satisfying power. However, there was no such fear for these waterwheels to begin with.

　　After all, all of them were only a knee-length tall.

　　Their dynamic power was pretty useless to begin with.

　　Aura crouched down, holding up the hem of her dress, and looked at the miniature waterwheels from above. At that very moment.

　　“Y- Your Highness! You have come by. I would have properly greeted you if you had told me beforehand!”

　　A middle-aged man with the beginnings of a paunch and a couple of young men with solid physiques came rus.h.i.+ng over to her.

　　Without catching their breathes, the craftsmen tried to prostrate themselves at once, but Aura shrugged her shoulders a bit and stopped them with a wink of her hand.

　　“Relax. It is a spontaneous visit. Sorry to trouble you with my whim.”

　　“Very well. How gracious.”

　　Although they didn’t go as far as prostrating themselves, the waterwheel artisans all lowered their heads deeply.

　　As Aura had no interest to waste time with unproductive actions, she spoke straightforward here, too.

　　“I have been told you also got some ‘results’. As far as I can see, though, six of the ten waterwheels are broken.”

　　“Why, indeed. Amongst the six broken waterwheels, five are of the traditional kind. The last one is a ‘new model’, built according to your instructions.”

　　“Then the remaining four intact waterwheels are all the new model?”

　　“Certainly.”

　　“The knowledge of my husband is impressive…”

　　Aura muttered that only to herself, so that those around her couldn’t hear it.

　　This continuous durability test for the waterwheels had been Zenjirou’s idea and realized by Aura as well.

　　Previously, when Aura had complained in front of Zenjirou how “their waterwheels broke faster than the ones on the Northern Continent”, he had casually remarked that “the numbers of teeth on the mes.h.i.+ng cogs were probably not coprime” and his opinion had manifested these ten miniature waterwheels.

　　The cogs being “coprime” to each other meant that the numbers of teeth on the mes.h.i.+ng cogs had no common divisor, except for the number one.

　　For example, nine and five were “coprime”, because their only common divisor was one. On the other hand, ten and five had five as an additional common divisor to one, thus they weren’t “coprime”.

　　For mes.h.i.+ng cogs it was an extremely important point whether the numbers of their teeth were coprime or not.

　　When the numbers of teeth of two mes.h.i.+ng cogs were “coprime”, then all the teeth geared with each other on the same probability. On the contrary, when they weren’t “coprime”, then only a few teeth geared with each other over and over again, whereas some teeth didn’t gear at all.

　　What kind of result would that produce?

　　In the “coprime” case, the two cogs would wear off evenly, allowing for an optimum usage. In the “not-coprime” case, some teeth would wear off most intensive, whereas some other teeth almost didn’t wear off at all, which quickly strained both cogs during a continuous usage.

　　A crooked cog would start to clatter before long and disintegrate soon after.

　　As a matter of fact, the average lifespan of coprime cogs was truly ten times longer than non-coprime cogs, even when they were made out of the same materials and with the same precision.

　　In the modern age of Earth, the cogwheels were made out of carbide with a micron-precise fineness, so its capability smoothed things over, even if the cogs weren’t “coprime”, but the cogwheels used in the waterwheels in this world were only made out of wood, a material that wears off easily, and when the accuracy had been done sloppily, too, the difference became painfully obvious.

　　“It is just as you have told me, Your Highness. Compared to the cogwheels I have built so far, the ones made in accordance with your instructions last a lot longer.”

　　Despite the fact that the Queen, an amateur on the field, had given them, experts on the field, an accurate suggestion for improvement, the craftsmen were honestly impressed from the bottom of their hearts without so much as adulating Aura.

　　Strictly speaking, the recognition was ent.i.tled to Zenjirou, not herself, so Aura felt a bit complicated inside, but she wasn’t so careless to let it show on her face now.

　　“Do not mention it. It was just a whimsical thought of mine. Without your expertise it could not have been done. If anything, I believe your ability to accept my proposal and realize it in such a short time, is all the more praiseworthy. Put out your skills for the Royal Family, for the Kingdom and for myself from now on as well.”

　　“Very well!”

　　The waterwheel artisans deeply lowered their heads once more in reaction to the words of the Queen.

　　Satisfied, Aura looked down onto the bowing craftsmen and showed a bright smile while continuing to speak.

　　“To keep to the point, I would like to implement this new cogwheel in the waterwheels on the royal domain next. I take that would be no problem?”

　　Aura sough confirmation, whereat the middle-aged artisan, still humbling himself to the best of his ability, answered with an appealing upward glance.

　　“Of course not. We can begin right away when you give the order. However, uhm… May I pose one question?”

　　“Mh? What is it? Speak up.”

　　She was more or less aware already what the waterwheel artisan wanted to ask, but she urged him to continue with feigned ignorance.

　　“Yes. With your permission, I will do so. Your Highness, do you intend to share the knowledge about the new cogwheel with the other feudal lords?”

　　The question was exactly what Aura had been expecting.

　　(I knew he would be bothered about that. Well, considering his standpoint, it is understandable.)

　　The new cogwheel had an overwhelmingly longer lifespan than the conventional cogwheel.

　　Its development was good news for the clients, namely royalty and n.o.bility, and for the consumers, namely farmers, but for a few others its existence meant a considerable harm.

　　Naturally, it affected the waterwheel artisans.

　　A longer durability of the cogs meant nothing else, but less work for them.

　　In a way, they were sc.r.a.pping at their own mainstay, so their worry was only natural.

　　Aura kept her poker face, even if she fully comprehended their inner turmoil, and replied in a casual tone.

　　“Yes, of course I will do so. As the ruler of the Kingdom, I have an obligation to share such benefiting information with my trusted subjects.”

　　“C- Certainly…”

　　Despair. The middle-aged craftsman looked like he was acting as a model for a sculpture with such a theme and spoke with a cracked voice.

　　Aura deliberately ignored how the artisan dropped his shoulders crestfallen and continued somewhat affected.

　　“Oh, right. This is an entirely different matter, but I am actually thinking of changing your commission system.

　　Right now, you only get paid every time a waterwheel or its repair is commissioned. However, my idea is to leave you in charge of the maintenance and supervision of the finished waterwheels and pay all the incidental expenses in advance at the beginning of the year.”

　　“Eh? That would mean…”

　　The waterwheel builder couldn’t comprehend her words right away, but before long, its meaning sunk in and his facial expression underwent another s.h.i.+ft.