With afternoon tea concluded, Jin turned to his guests.
"Well, there's still some time before dinner, so if anyone has a request, I'm all ears. Otherwise, I was thinking you could all relax in the hot spring."
"Um, we still have tomorrow, right?" Rubina was the first to ask.
"Yes, that's right. Considering the time difference, if we head back after dinner tomorrow—around 7:00 PM—it will be 7:00 AM on Onogoro Island."
"...I might end up short on sleep." Being young, Rubina was particularly sensitive to a lack of sleep.
"If you're worried, take a thirty-minute nap later and go to bed early tonight. That should help prevent jet lag," Jin advised.
Since there were no other requests, they decided to soak in the hot spring and relax, chatting until it was time for dinner.
＊ ＊ ＊
"Phew."
"So this is a hot spring..."
"I have bathed in them several times in other lands, and they are quite wonderful."
Jin, Shu, and Trihart were in the men's bath. Given his position, Trihart had traveled to the outside world many times and had experienced hot springs before, but it was Shu's first time.
"Are there no hot springs on Onogoro Island?" Jin asked. He recalled that the bath he had used on Onogoro hadn't been a natural spring.
"I wonder if digging underground on Onogoro would work." Jin mused that if they dug deep enough, they would likely find groundwater heated by geothermal energy.
"Perhaps the founders decided that a normal bath was sufficient without going to such lengths," Trihart suggested. "Or perhaps the water quality simply wasn't to their liking."
It was a fact that not everyone enjoyed them; some people couldn't stand the smell of sulfur and avoided sulfur springs, while others with sensitive skin found acidic springs uncomfortable.
Jin vaguely imagined that the real reason likely lay in the subterranean structure of Onogoro Island.
＊ ＊ ＊
Twenty minutes after the men had finished, Rubina, Natalia, and Susanne emerged from the bath.
The time was 4:30 PM. Since dinner was scheduled for 7:00 PM, they decided to enjoy some cold, fresh juice after their soak.
"Wow, this is delicious!"
It was carbonated ramon juice. It wasn't too sweet, and its moderate acidity was refreshing.
"I figured you'd be used to drinking coffee milk over there," Jin noted.
"That is true. And if we drink something too sweet now, we won't be able to enjoy dinner, so this is just right," Susanne agreed.
As twilight approached, a peaceful atmosphere filled the dining hall of Hourai Island.
Dinner consisted of white rice, miso soup with aburaage and okara, grilled dried aji—a fish looking just like horse mackerel—sweet tamagoyaki, hamburger steak, oshinko, and tempura. Since children were present, there was no alcohol.
"I love hamburger steak! And this sweet tamagoyaki is amazing!" Rubina seemed to have taken a great liking to the sweet tamagoyaki.
"Oh, this dried fish is... how should I put it... deeply flavorful," Trihart said, surprised. Seeing his reaction, Jin decided to ask something that had just occurred to him.
"Don't you make dried fish on Onogoro Island?"
"We do," was the reply.
When Jin asked how, they explained that after bleeding and butterflying the catch, they dried the fish using magic.
"It is much quicker that way, and insects do not swarm around it."
Jin nodded, understanding. "Ah, so that's why."
"Pardon?"
"Dried fish isn't just about dehydration. By exposing it to the sun and letting it dry slowly, protein decomposition results in amino acids, which create the umami flavor."
Susanne nodded repeatedly, looking impressed by the explanation. "Is that so! So it is not always best to finish a task in the shortest amount of time..."
"This salt is delicious," Natalia remarked, noting the seasoning on her tempura.
"Don't you make seaweed salt?"
"Seaweed salt?" From her reaction, it was clear they didn't.
"Ah, the Inner Sea of Onogoro Island has very little seaweed, doesn't it?" Jin realized.
Because of the coral reefs, seaweed was scarce. The water was clean, so they could produce good salt from the sea, but it couldn't quite compete with the richness of seaweed salt when used as a garnish for tempura. Jin took a moment to explain how seaweed salt was produced.
"I see, so the umami from the seaweed is added to the salt."
"Exactly. Animal umami comes from inosinic acid, and plant umami comes from glutamic acid... I think? Well, the effect is more important than the name." Jin’s memory on the specific chemical names was a bit fuzzy.
"We can hardly harvest seaweed ourselves, after all," Natalia said, looking a bit disappointed.
Jin smiled. "Alright. Tomorrow, we're going for an underwater excursion."
"Pardon?"
"An underwater excursion?"
"Yeah. We'll be using a submersible I built called the Shachi."
It was ten meters long, three meters wide, and could carry eight people. The structure was made of 64 light silver, while the outer plating was a two-layer composite of Gigant Peeder shell and 64 light silver. The interior was coated with soft magi-resin for leak prevention and emergency repairs. Its propulsion came from Aqua Thrusters and Force Generators.
The vessel was heavily equipped, featuring two underwater magi-cannons for torpedo-type shells and several mana bomb torpedoes.
Laojun, being thoughtful, displayed the blueprints for the Shachi on the Magi-screen embedded in the dining hall wall. It showed a three-view drawing using third-angle projection along with a detailed sketch.
"...That is incredible."
"This is quite something else..."
"As expected of you, Jin-sama!"
After hearing the specifications, the guests were left in a mix of shock and reverence.
"Since it seats eight... if we have Edgar serve as the pilot again, then counting me, Reiko, Rubina, Natalia, Shuuki, Trihart, and Susanne... that makes exactly eight."
Unfortunately, the assistant golems like Arrow and Donner would have to stay behind. However, even without Jin needing to persuade them, everyone accepted that it couldn't be helped.
"I want to ride it already!" Rubina was practically vibrating with excitement.
"...Wait until tomorrow, okay?" Jin said, trying to temper her expectations.
But he imagined that Rubina probably wouldn't be able to sleep a wink tonight. She looked exactly like a child on the night before a long-awaited school field trip.