After finishing the pens, Jin decided it was time to teach Elsa how to make rubber balls.
Land A had already returned with the sap collection containers they had set up the previous day.
"Listen closely, Elsa. This is raw rubber."
"Raw rubber..."
Elsa stared curiously at the sticky, white liquid that had pooled in the container.
"If you leave it like this, it turns into a gooey mess when it's hot and hardens when it's cold. There’s a specific way to give it a consistent level of hardness."
"..."
Elsa listened with a serious expression, absorbing every word.
"You do it by mixing in sulfur. I’ll explain the scientific reasoning some other time. For now, just know that you need to mix in about fifteen to twenty percent sulfur by weight."
"Mm."
Jin transferred some of the raw rubber into a smaller container and held out a lump of sulfur.
"I’ll demonstrate first."
With that, Jin used Analyze to determine the weights of the raw rubber and the sulfur.
"The raw rubber is about 250 grams, so I’ll need roughly 38 grams of sulfur."
He prepared the required amount of sulfur by applying Separation to the larger lump.
"Now, we mix them. Homogenize. And then, Heat."
Heating the mixture once the sulfur was uniformly dispersed triggered a reaction called cross-linking. This transformed the raw rubber into stable rubber, meaning it would no longer melt when exposed to heat.
"Finally, Forming. At this stage, you have to get air inside. To do that, you make one part of the material extremely thin for a split second."
An extremely thin rubber membrane contained countless microscopic holes, just enough for air to pass through. By pulling air inside through those pores and then instantly increasing the thickness of the membrane again, the air became trapped.
"Then we use Surf Treatment to make the membrane dense and airtight. And with that, the ball is finished."
He completed the process to ensure no air would leak, and a dodgeball was ready.
Elsa had seen the village children playing with balls before, so seeing one created from scratch made everything click for her.
"Now, why don't you give it a try?"
Since it was her first time, Jin handed her about 80 grams of raw rubber to start with a small batch. The first task was to prepare exactly 12 grams of sulfur.
"Remember what we practiced before? Focus on the sensation of a single gram and build up from there."
"Mm."
Elsa concentrated, recalling the weight of a single gram and adding it together twelve times in her mind. The moment that mental image solidified, she spoke.
"Separation."
She extracted the exact amount of sulfur required. Seeing this, Jin offered his praise.
"Yeah, well done. There’s almost no margin of error. That’s impressive, Elsa."
Beaming at the praise, Elsa continued the process.
"Homogenize. Heat."
"That’s it. Don't forget to keep a close eye on the state of the rubber while you’re heating it."
"Mm."
After a minute of careful heating, the rubber was perfectly formed. Once the material reached this state, shaping it into a ball was child's play for her. She performed the surface treatment without a hitch, and a single baseball was complete.
"Success on your very first try? You've really improved, Elsa."
"It's thanks to Jin-nii."
"With this, we’ll be fine even if the kids start clamoring for more balls."
"Mm. Leave it to me."
Seeing Elsa nod firmly, Jin stood up. It was nearly lunchtime.
Just as they stepped out of the workshop, Hanna arrived to call them. Jin and Elsa washed their hands and headed to the dining room at Martha’s house.
"Ah, Jin-sama."
There were more chairs in the dining room now, and Barrow and Belle were already seated.
"Um, well, Martha-sama said it was alright for us to eat with everyone."
Barrow still seemed a bit nervous. Jin replied with a reassuring smile.
"Yeah, of course. Once you get used to things here, why don't you try cooking at the castle every now and then?"
When Jin suggested this, Belle answered energetically.
"Yes! Martha-sama and Mine-sama are teaching us how to cook right now!"
"I’ve also been learning a few dishes in the Celuroa Kingdom style," Mine added with a smile.
Then, Barrow spoke up hesitantly.
"Um... Jin-sama? May I ask a few questions?"
Jin, who had just put a piece of bread in his mouth, nodded to show he was listening.
"Y-Yes. Well, um... this is... the Klein Kingdom, right?"
"Hm? Yeah, that's right."
Having swallowed his bread, Jin gave a proper answer this time.
"Th-Then, well... how did you bring us... hundreds of kilometers away... from Toscosia... to the Klein Kingdom...?"
Perhaps intuitively sensing that he was overstepping, his voice trailed off until it was barely a whisper.
"Ah, I see. Well, it’s a natural question. For now, let’s just say there’s a way to do it. We can discuss the details later on."
When Jin gave his vague answer, Belle was the next to speak.
"Right! It’s because you have to see if we're trustworthy first! We’ll do our best to prove ourselves!...Come on, Barrow, you say it too!"
"U-Um... I’ll... do my best..."
Barrow was promptly scolded for his lack of spirit and told to say it again with more energy. Jin watched them with a faint smile; it was clear that Barrow was already completely whipped by Belle.
After lunch, Butler B and C arrived. It seemed Laojun had already dispatched them. Barrow and Belle headed back to the castle along with the two golem units.
At this rate, the Five-Colored Golem Maids had likely arrived as well. Jin could already imagine the look of shock on Barrow’s face.
"Belle certainly has the better adaptability..."
Jin thought to himself, though he didn't realize that rather than "adapting," she was simply throwing common sense to the wind.
"Ah, Jin-san, how are the pens coming along?"
Roland and Beaute arrived just then.
"Oh, they’re finished," Jin said, returning from the workshop with a box filled with pens.
"Thank you. You truly are a man of your word, Jin-san."
Roland accepted the box with a pleasant smile, while Beaute stood behind him, his eyes wide in disbelief at the speed of production.
"I had Elsa help me, after all."
Jin introduced Elsa properly this time, as they had only briefly met before.
"I’m his sister figure, Elsa."
Roland was a bit caught off guard by the term "sister figure," but being a seasoned merchant, he let it slide without a word.
"Elsa-san, is it? I look forward to working with you."
"Likewise."
Now that the introduction was finished, Jin made a final point.
"The production speed will be lower than mine, but Elsa can also make pens and balls. That way, everything will be fine even if I’m not around."
Roland was delighted. Apparently, he had been pestered quite a bit by customers who were desperate for the balls.
"Regarding the price for the pens, how does 200 Tolls for a nib and 500 Tolls for the integrated type sound?"
It was typical of Jin not to negotiate the price beforehand, but Roland had suggested a very fair, conscientious price.
If the price were too low, it might drive traditional products out of the market entirely, leading to a monopoly or causing financial ruin for those who made a living from older goods—factors that could hinder healthy economic development. Whether Roland had actually thought that far ahead was something only he knew.
"Yes, that sounds fine to me," Jin agreed easily.
Mine, watching from the side, thought that once Barrow and the others were more settled, they should be tasked with supporting Jin in these business matters.
The price for the balls remained the same as before, and Jin accepted the payment. He immediately turned around and entrusted the entire sum to Mine.
"I’ll keep this safe for you. Jin-sama, if that is the case, would it be alright if I also worked at the castle?" Mine asked. She clarified that she wouldn't be able to be there all the time—essentially, a part-time position.
"Yeah, Barrow and Belle probably aren't used to things yet, so that would be a huge help."
Since it was a perfect arrangement, Jin agreed without hesitation.
"It would be even better if you could help educate those two a bit. Would one gold coin a month be alright for your salary?"
That was 10,000 Tolls—roughly 100,000 yen. Considering that monthly food expenses in this village didn't even reach 1,000 Tolls, it was a more than generous amount.
Mine argued that it was far too much since she wouldn't be working full-time, but Jin wouldn't hear it.
"I'm always leaving you in charge while I'm away, and I’ll likely be gone quite often in the future, too."
Having settled the matter, Jin noticed it was already past one o’clock.
"Well, I have to be going now."
He headed not for the shelter, but for the workshop basement. Since Roland and his companion had already departed, there was no one left to find his disappearance suspicious.
"Well then, I’m off."
"Take care, Onii-chan!"
"Take care, Jin-nii."
"Be careful, Jin."
"Have a safe journey, Jin-sama."
With everyone seeing him off, Jin transferred away to rejoin Reinhard and the others.