May 3460.
"Look, Mio, over here!"
"Yuu, this way, over here!"
In the meadows of Kaina Village, Jin and Elsa were out playing with Yuu and Mio.
Even so, the two children were not yet a year old and could only manage a tottering waddle. Watching them walk haltingly across the young grass toward their parents was the very definition of heartwarming.
"Abuu!"
"Daa!"
Since they were on the grass, it didn't hurt even if they tumbled, and with Elsa right there, any minor scrapes could be healed instantly.
The sunlight in early May was still soft, making it a perfect day for playing outdoors.
"Toh!"
"Oh, Mio wins!"
A second faster than Yuu, Mio dove into Jin's arms.
"Uuu..."
Yuu likewise fell into Elsa's embrace.
Yuu had blond hair and light blue eyes inherited from Elsa. Mio, meanwhile, had black eyes and black hair, the spitting image of Jin.
"Onii-chan, it’s almost time for lunch."
"Oh, is it that time already?"
Thanks to Hanna coming to call them, Jin and Elsa—who had been completely absorbed in playtime—realized it was already midday.
"Ah, they’re back. Hey there!"
Saki, who was visiting Kaina Village, spotted them and waved from the dining room window.
"Hey, Saki. Sorry to keep you waiting."
"Honestly. I was starting to get tired of waiting."
"My bad, my bad. But Saki, you got back sooner than I expected, didn't you?"
Saki had been out in the mountains since morning with Hanna as her guide, searching for rare materials. Naturally, she had been using a Golem horse.
"Yeah. That horse is great. Even I was able to tour the deep mountains with ease."
"So, did you find anything?"
Saki grinned at Jin's question.
"Kufu, I'm glad you asked. Take a look at this!"
Saki reached into the bag at her feet and lined up several specimens on the table. They looked like chunks of ore.
"This one is silver, and this one is zinc ore. In other words, there's a high probability we can develop a mine here!"
"Goodness me, Saki-chan. You shouldn't be lining up rocks on the table where we're about to eat lunch."
Martha arrived carrying a pot and scolded Saki with a wry smile.
"Ah, s-sorry! I'll put them away right now!"
Saki hurriedly stuffed the ores back into her bag.
Hanna wiped the table without a word. Martha set the pot down with a thud.
"It's the oden Jin taught me! Take as much as you like on your plates....Ah, Saki-chan, go wash your hands again."
"Y-Yes!"
At Martha's command, Saki rushed out of the dining room to wash her hands.
Even though it was May, Kaina Village was located in a high-latitude region, so the hot oden was still delicious.
"Ah, this is tasty!"
Saki seemed to have taken a liking to the chikuwabu.
"I love this one!"
Hanna was eating a kombu roll.
"I prefer this myself."
Martha seemed to favor the hanpen.
"I'm partial to the daikon once it’s soaked up all the broth."
Jin was sensitive to heat, so he blew on his daikon to let it cool before taking a bite.
"I like the tsumire."
Elsa seemed to prefer the fish balls.
As for Yuu and Mio, they were currently quite content being fed a fruit paste made from Persica and apulul as weaning food by Reiko and Anne.
After the meal, the group settled into a relaxed conversation.
Having filled their bellies, Yuu and Mio were down for their midday nap, with Elsa and Anne staying by their side.
"How are things on your end, Saki? We haven't seen each other lately. Have you been busy?" Jin asked.
"Yeah, pretty busy. I've been commissioned by the state to develop a new material."
"Huh, what kind?"
"A lightweight cushioning material. Apparently, they want to be able to use it for things like hot air balloons."
"Lightweight, huh..."
Peruhya rubber and natural rubber already existed, and it was becoming common knowledge among certain alchemists that rubber hardness could be adjusted by varying the amount of sulfur mixed in.
However, rubber was heavy.
While it wasn't an issue for ground use, materials needed to be as light as possible for hot air balloons or ship seats.
The specific gravity of rubber ranged from about 0.9 to 1.2 depending on the type, with some being even denser. In other words, it was almost the same as water, and some varieties would even sink.
"I was wondering if I could do something clever using the magi-polyethylene I developed previously."
"That sounds like a good idea."
The specific gravity of polyethylene was also around 0.9 to 0.97, depending on the density. However, it had almost no water absorption, so it was hardly affected by humidity.
The physical properties of magi-polyethylene were the same as regular polyethylene, but when reinforced with mana, its durability increased exponentially.
"I was thinking if I could make it porous like a Gula Schwamm..."
"Ah, like a foamed material!" Hanna said, having been listening to the conversation nearby.
"Yeah, exactly. I want to make a foamed material," Saki replied. "I thought I could just melt it and mix in air, but..."
"Saki-oneechan, why not try applying pressure?"
"Eh?"
"This is just my imagination, but what if you apply pressure to the melted magi-polyethylene and then release it? Wouldn't that create a lot of bubbles, like carbonated water?"
"That's it!"
Saki clapped her hands in delight.
"We can experiment using a pressure cooker!"
Saki looked ready to bolt for the Warp Gate right then and there, but Jin grabbed her by the shoulder and stopped her.
"Wait....Listen, you came here to rest because the fatigue from working day after day finally caught up with you, right? I'll let the mineral hunting slide, but you’re staying here for the rest of today."
"Uuugh... Jin, that's heartless... Let me go home..."
"The. Answer. Is. No."
As Saki slumped her shoulders in defeat, Hanna offered some comfort.
"Saki-oneechan, cheer up. I'll guide you to the East Forest next."
At those words, Saki lifted her head.
"The East Forest... That's the place with lots of Peruhya trees, right?"
"Yup."
"All right. Hanna-chan, I'm counting on you!"
And so, Saki and Hanna headed for the East Forest.
Jin ordered the guardian golem of Kaina Village, Gon, to follow along and act as their guard.