On July 20th, rain had been falling over Hourai Island since morning.
"Well, I suppose we have days like this too," Jin remarked, gazing out the window of the House at the rain-shrouded laboratory.
"Mm. A rainy day once in a while is nice," Elsa quietly agreed.
Today, the other members of the Jin Family were each spending their time as they pleased.
"Haha, now this is a result I can be proud of!!"
"Oh, isn't that Rai-nii's voice?"
"I wonder if Reinhard's making something."
"Mm. Now that he doesn't have to manage his territory anymore, he can do whatever he wants..."
"Ah, right."
Hourai Island truly had become a sacred ground, Jin mused with deep emotion.
It might be slightly different from what the Predecessor had imagined, but even so, people whose true callings lay in creation, research, and inquiry had gathered here.
Watching the falling rain, Jin idly wondered if this wasn't the very ideal she had once dreamed of.
"My Lord, I apologize for interrupting your leisure, but I have a report."
Laojun's voice resonated through the room.
"Whenever you start like that, it's usually something urgent... Let's hear it."
"Yes, very well. It concerns the Sondes deployed to measure the high-concentration free ether space."
"Did something happen?!"
"No, nothing of that sort. However, their primary communication functions are failing to operate."
"What?"
"We positioned six Sondes near the boundary surface of the spherical high-concentration free ether space, but..."
"Yeah?"
"They are unable to communicate with one another."
"Why would... Ah, is the high-concentration free ether space blocking the ether waves?"
"That is correct."
"I completely overlooked that..."
Ether waves evidently could not penetrate a high-concentration free ether space.
"Sound waves and the like can still propagate even in dense media, so I assumed a powerful magi-communicator would manage just fine."
Jin pondered the dilemma for a moment.
"Jin-nii, wouldn't it be simpler to just increase the distance?" Elsa suggested from beside him.
"That's a good point. Since our goal is simply measuring the high-concentration free ether space, that might be best."
Presently, six units were positioned near the boundary of the roughly spherical space, aligned with the vertices of an octahedron.
"What if we add two more and place them at the vertices of a cube bounding the sphere?"
"That should work."
They would only need to control the Sondes so that the virtual square planes formed by sets of four units remained tangent to the sphere's surface.
By monitoring the coordinates of those eight Sondes, they would easily determine the diameter of the high-concentration free ether space.
"Let's go craft two more right away."
Curing his rainy-day boredom, Jin set off toward the laboratory.
He took a Warp Gate to avoid walking through the downpour.
Watching his retreating figure, Elsa smiled softly.
"All right, Reiko, give me a hand."
"Yes, Father."
With Reiko assisting him, Jin quickly finished assembling two additional Sondes.
Since they were identical to the previous models, it took less than thirty minutes.
"That does it. Laojun, deploy these two."
"Understood."
Jin let out a relieved breath.
With this, their survey of the high-concentration free ether space should proceed much more smoothly.
"Now then, what's Reinhard up to?"
Having finished his own work, Jin grew curious about what had made Reinhard shout earlier and peeked into the neighboring workshop.
"Reinhard, what are you working on?"
"Ah, Jin, Reiko-chan! Take a look at this!"
"Let's see here..."
Sitting on the workbench was a magi-device featuring six legs extending from a disc-shaped body roughly 30 centimeters across. It looked vaguely insectoid.
Or rather, strip away the legs, and it would look just like a robotic vacuum cleaner.
"It's an underground resource exploration golem!"
"Underground resources?"
As Jin echoed the words, Reinhard nodded with utter satisfaction.
"Resource shortages have become a serious problem in the Shouro Empire, haven't they? So I decided to build this."
"I see."
Its core functionality was likely Grand Search, Jin deduced.
Designing a golem without a humanoid silhouette was quintessentially Reinhard.
Jin, by contrast, remained stubbornly attached to human shapes. His rare exceptions were the mermaid-type Mermaids, Golem horses, and cat-type golems.
(Oh, and the glider golem too, I suppose.)
Regardless, Reinhard had clearly been fretting over his homeland's resource scarcity in his own way.
"The real question is how to supply these to the Shouro Empire."
That was the immediate hurdle.
"The obvious route would be through Avalon, but..."
Channeling them through Avalon meant they couldn't give preferential treatment to the Shouro Empire.
This magi-device was something Reinhard had built purely out of devotion to his homeland.
"Why not present it directly to Her Majesty?"
"That's an option, but I'd really like to see how my territory is doing first."
Reinhard's territory had originally been Kalts Village, but it had since grown into Kalts Town.
Considering his current standing in a count's family, the land was undeniably too modest, but according to Laojun's reports, the difference was made up through a hereditary stipend.
"In that case, why don't we go take a look?"
"Wait, is that really all right?"
"Nobody recognizes your face anymore anyway. As long as you don't use your real name, there shouldn't be any problem, right?"
"...I suppose that's true."
Agreeing that a bit of discretion regarding their identities was all they needed, Jin and Reinhard settled on a plan.
"In that case, allow the Quinta to serve as your guides."
"Oh, good idea."
"Would it be acceptable for Elsa-sama and Berche-sama to accompany you?"
"Yeah, sounds fine."
Jin figured taking the whole household would attract far too much attention.
"Ah, I'd like to come along too!"
Saki raised her hand, eagerly volunteering.
"Right, your family home is nearby as well, Saki."
With that, Saki joined the expedition.
Deciding the party shouldn't grow any larger, Toa chose to stay behind.
"I'd like to make sure the others get a chance to visit their old hometowns and places dear to them too."
"That would be quite wonderful."
Though Jin had merely been thinking aloud, Laojun chimed in with approval.
"Having Reiko-san along as an escort should be sufficient, correct?"
That left only the question of travel.
"Should we fly openly aboard the Hurricane, or slip in discreetly through a Warp Gate?" Jin asked to gauge Reinhard's preference.
"Hmm, let's see... Let's make an entrance and go openly this time."
"Understood."
With their course set, Jin and the others began preparing for the trip.