The time was 2:00 PM, and Jin, Elsa, Reiko, and Hope were continuing their stroll through the town of Coco.
"There is a pump here as well," Reiko remarked. "Though, as expected, it appears to have been manufactured recently."
The suction pump was an invention Jin had originally crafted back in Kaina Village. It seemed simple everyday tools like this had managed to escape eradication by the Magic Federation.
"I wonder if we need to keep developing ordinary tools, not just magi-devices..."
"Aren't those kinds of things imported from Mitsuho?" Elsa asked in response to Jin's musing.
"That might be true, but for some reason, tools originating from Mitsuho don't seem to have caught on very well."
Take the bicycle, for instance. While widely used in Mitsuho, it had barely gained any traction in the Allied Kingdoms, nor in the Shouro Empire.
"Maybe it's just personal preference?" Elsa suggested, though Jin doubted that was all there was to it.
"Hmm..." Lumping it all under "preference" felt far too vague, so Jin voiced the thought that came to mind. "Could it be that things without a trace of magic just aren't well received?"
"Nn. That might be possible."
In the case of the pump, it had been welcomed by commoners who couldn't use magic. But bicycles were targeted at the wealthy and above, which made all the difference.
"Developing a market really is hard work."
"Nn."
Conversing as they walked, Jin and Elsa continued their tour of the town.
"Ah, an automobile."
From the direction Elsa pointed, a single Golem automobile came cruising down the street.
"I don't recognize that model."
"It was likely made in the Shouro Empire," Reiko informed him.
"I see. So those are catching on, then."
"Because they utilize magic."
"Then instead of bicycles, would something like a magi-bike be more popular?"
"Well, that is hard to say."
If people couldn't even ride a bicycle, there was no way they could suddenly handle a motorbike. Jin ultimately concluded that widespread adoption would be difficult.
They continued exploring the town after that, but turned up no further insights. Inspirations for tools and magi-devices didn't just strike on a whim, so at 3:30 PM, Jin and his companions headed back to Chidoritei.
"I feel like most of the things I've made up until now were born out of necessity," Jin murmured, sipping tea in their room.
"Nn, that might be true."
As the saying went, necessity is the mother of invention. That was likely why introducing something from elsewhere just because it seemed convenient rarely caught on.
Anticipating a crowd of guests later, Jin and Elsa decided to use the baths while it was still daylight. The bathhouse was in a separate building and was quite spacious. In this cold season, a hot bath was a true blessing. Had the inn lacked one, Jin would have likely used a Warp Gate to return to Hourai Island for a soak.
"Ah, what wonderful water."
It was currently 4:00 PM. Since no one else had entered the bath yet, Jin had the first dip to himself. Elsa had the same luck on her side, and both enjoyed a peaceful, undisturbed soak.
Dinner was a lavish spread of traditional Kingdom of Franz cuisine. Jin and Elsa finished every last bite, reminiscing about the old days... back when they had visited with Sion and the others.
Afterward, while relaxing in their room, they decided to hear what Reiko had learned about the fireworks.
"Well, you see..." Reiko began. "It is said that the origin of fireworks lies in Mitsuho."
Indeed, Mitsuho was heavily influenced by the Magus culturally. The Guide, Akitsu, was one such example. As a former medical student with abundant knowledge of chemistry, it wouldn't have been unusual for the Magus, Shuuki Tsetse, to have recreated fireworks. Alternatively, he might have passed down the concept for someone in a later generation to recreate. Both possibilities were entirely plausible, Jin reasoned.
However, the truth was about to surprise Jin even further.
"The fireworks... the aerial shells were recreated in this world by Father and Lady Saki."
"What?!"
According to Reiko, it had been the Jin of four hundred years ago—specifically, when he was around forty—who had developed them in collaboration with Saki, Laojun, and the Smiths.
"...Elsa, did you know about this?"
"...Nn. Sorry for keeping quiet. But I really had no idea why they ended up being launched here, at the Klein Kingdom checkpoint."
"I see." Jin recalled that what had piqued his curiosity earlier was why they were being launched here, having never asked who made them in the first place, so he didn't press the matter.
"Now then, regarding what Father was curious about—the reason why they launch fireworks..."
"Yeah."
"It seems the practice originated from beacon fires used to signal that the border was secure."
Jin nodded, understanding the logic. Without magical communication methods, visual signals like that were remarkably effective. Four hundred years ago, the Klein Kingdom and the Kingdom of Franz had clashed in repeated skirmishes until the House of Lafayette inherited the throne. That was undoubtedly why such a means of communication had been chosen.
"Even after peace was established, the beacon fires were maintained as ongoing proof that the border remained peaceful and secure." Over time, it turned into a mere ceremonial event, and Reiko explained that an attempt had eventually been made to change the color of the smoke.
"I see."
"However, adding color to smoke proved to be quite difficult."
"I imagine so."
"Therefore, although their name has been lost to time, a certain engineer turned their attention to fireworks."
"So that's how it went... Which brings us to the present?"
"No, not right away. At first, they launched the fireworks during the day, but..."
"Ah, the visibility was poor, wasn't it?" Jin smiled wryly to himself. No matter how pretty a firework was, launching it in broad daylight was an utter waste.
"Yes. When they tried launching them at night, the display was magnificent, so from then on, the fireworks were set off after dark."
With that, Jin was finally convinced.
"Over the past century of peace, the beacon fires ceased altogether, leaving only the custom of launching fireworks for two days during this season when the air is crisp and clear."
"So they don't do it in the summer, then."
"Apparently, it gets surprisingly windy in the summer."
A strong wind blowing during a fireworks launch was certainly far from ideal. Hearing that explanation, Jin found himself nodding in agreement.
"And what about the two-day duration?"
"It seems the engineer who introduced the fireworks decided upon it, but precise records regarding that detail have not survived. I apologize."
"No, it's fine. That makes plenty of sense."
Jin warmly thanked Reiko, as well as Laojun for compiling the information.