On the morning of December 23rd.
Jin, Reiko, Elsa, Edgar, and Reinhard stood in the square before the Imperial Palace in the capital of Loizart.
"Well then, Lord Reinhard Randol, Lady Elsa Randol, I wish you success in your duties."
"Y-Yes, Your Majesty."
The Empress herself presented the personal letter addressed to the Kingdom of Elias to Reinhard, the lead ambassador.
"Lord Jin Nidou, I leave the two of them in your care. Though with Reiko-chan around, I suppose there is nothing to worry about."
"Ah, yes."
Halfway through her sentence, the Empress’s tone suddenly shifted to an informal one.
"One more thing. I expect the Bernstein to arrive at Port Rock this evening. Therefore, I would like you, Jin-kun, to arrive on the 24th—one day later."
"Eh?"
Jin, who had fully expected to be there to welcome the Bernstein, was surprised by the Empress's unexpected request. However, he was convinced by the explanation that followed.
"I know your airship is fast, Jin-kun. But you see, if you depart later than the new ship and yet arrive before it, I think the crew would be quite disappointed."
Certainly, flaunting superior performance for no good reason served no one's honor. Jin nodded in agreement.
"I understand. I will adjust our arrival time at Port Rock."
Upon hearing Jin's reply, the Empress smiled radiantly.
In truth, thanks to further refinements, the airship was now capable of safely traveling at speeds of up to 150 km/h when using the wind-shielding barrier and the force generator.
＊ ＊ ＊
The group departed Loizart aboard the airship. Once they had reached a sufficient altitude, they moved to Hourai Island via a Warp Gate.
With Steward at the helm, the airship then set a course toward the Kingdom of Elias. For appearances, they intended to claim they had spent the day camping in the mountains or fields of the Celuroa Kingdom.
As for what they did while at Hourai Island...
"Oh! So this is the Shachi!"
It was to give Reinhard a ride in the submersible.
"Hehe, I’m looking forward to this."
Since Saki was also visiting, they naturally invited her. There was no way she would refuse, so Jin, Elsa, Reinhard, and Saki all climbed aboard. Reiko took her place as the pilot.
Since its last voyage, the air conditioning and oxygen supply systems had been improved.
Specifically, Jin had realized that most of the moisture in the cabin's humidity—$H_2O$—came from the occupants' breath. Simply scrubbing $CO_2$ was insufficient; the system had been modified to extract oxygen from the humidity as well. Furthermore, it could now even extract oxygen from seawater in case of an emergency.
"If you start to feel uncomfortable, tell me immediately. Also, for evacuation, we have this Warp Gate..."
After a brief explanation of the emergency equipment, they departed.
"Oh! This is a novel sight!"
Reinhard voiced the same awe Jin had felt during his first trip. As for Saki, she was intensely curious about the seabed.
"Hehe, last year I could never have imagined that a day would come when I would see such a landscape."
The Shachi was currently cruising at a depth of about 100 meters. The gently sloping continental shelf gradually fell away into the depths.
"Oh? What is that?" Reinhard called out at a depth of around 200 meters. He pointed toward a specific spot on the seafloor.
"Ah, that's an underwater resource mining site."
"I see..."
The underwater resources had been discovered during the Shachi's first deep-sea dive, but once they started searching in earnest, excellent mineral deposits were found in various places, including the shallows.
The Mermaid unit was the heart of the operation. Ten units, numbered Mermaid 21 through 30, were conducting the mining here. The mined ore was sent to Shinkai via a Warp Gate floating on the surface.
Five Smith units were stationed at Shinkai; they sorted the incoming ore, smelted it, and then forwarded the refined materials to Hourai Island. The slag was sent back and used to refill the excavated holes.
"Hmm, it's quite impressive," Reinhard noted, fascinated by Jin's explanation.
"Have you found any interesting ores?" Saki's interest was purely scientific.
"We've only just started, so no rare minerals have turned up yet..."
Since there wasn't much to see from a distance, they decided to inspect the mined ores later, and the Shachi moved on.
The depth exceeded 200 meters, eventually reaching about 300. Because sunlight did not reach this far, it was quite dark. As they proceeded with the searchlights on, fish illuminated by the beams fled in startle—a sight they never grew tired of watching.
"My, this is fascinating... but I suppose we should head back soon..." Reinhard said with a hint of regret. He was, after all, on official business and couldn't spend the whole day playing.
"Shall we go back?"
"Mm."
And so, the Shachi made a U-turn and returned to Tatsumi Bay.
＊ ＊ ＊
"Man, Jin, it was only for a short while, but I had fun!"
"Yeah, yeah, I had fun too."
Reinhard and Saki were in high spirits upon their return to Hourai Island. Saki even rushed off to the Warp Gate where the underwater resources were delivered to see if there were any unusual materials to study.
"Saki is the same as ever," Reinhard said softly, narrowing his eyes with a smile as he watched her go.
"We'll stay at the Mansion tonight and transfer to the airship tomorrow morning," Jin said as he wrote the schedule on a whiteboard.
Since Hourai Island was further east than their destination of Port Rock, he wanted to be careful with the time zone calculations to avoid any future confusion.
"Yeah, I understand....I'm looking forward to the food on Hourai Island, too."
Soleil, Luna, and Perido Leader had become exceptionally skilled at cooking, and they had a firm grasp on the appetites of the Jin Family.
Reinhard and Saki took a sip of the miso soup served at the table and both wore looks of shock.
"Wh-What deliciousness!"
"This is different from what we usually eat!"
Jin laughed and explained. "Ah, that's because the dashi was properly made with katsuobushi."
The level of quality was incomparable to what was served in Loizart.
"The foreigners... no, it was the Mitsuho Kingdom, right? They have a culture that creates such things?"
"Yeah. Apparently, they have many more unique things like it."
"I am interested."
Reinhard looked like he wanted to visit for a moment, but their course was already set for the Kingdom of Elias.
"Well, things will become clearer soon enough."
John Dini was currently infiltrating the area, so more information was bound to arrive.
＊ ＊ ＊
As planned, at noon on December 24th, the group prepared to leave Hourai Island.
"Jin, Reinhard, Elsa, Reiko-chan, Edgar, have a safe trip. I'll be enjoying myself sorting through the ores," Saki said, seeing them off as they stepped into the Warp Gate.
In an instant, they transferred and appeared inside the airship piloted by Steward.
"Steward, roughly where are we now?"
"Yes, Master. We have just passed over the Kingdom of Egerea and are about to reach the Kingdom of Elias."
Looking down, they could see the blue marine and a large peninsula.
"Alright, lower our altitude a bit."
"Understood."
They descended to an altitude of 400 meters—a height low enough to be visible from the ground. Since few people spent their time looking at the sky, they arrived at Port Rock at 3:00 PM local time without causing much of a stir.
As they descended toward the familiar central square, it seemed word had been sent by the Empress, as a welcoming ceremony was already being prepared.
"...There's quite a crowd."
Jin felt a bit overwhelmed. The square, except for the landing space, was packed with people.
"Well, that's only natural. We're likely the first people they've ever seen arrive by flying through the sky."
The Kingdom of Elias had not experienced the recent Unifilar incident, so they had never seen their hot air balloons either.
"Ah... true. If we had arrived earlier than the Bernstein, their feat would have been completely overshadowed..."
Once again, Jin was struck by the Empress's foresight and thoughtfulness.
Welcomed by the deafening cheers of the crowd, the airship landed slowly in the center of the square.