25. Welcome Home System

Subtitle is arbitrary.

With safety checks within the compound complete, at 7 a.m., just as at the time of the fusion power plant’s launch, two general-purpose work craft descended from above. They began dispersing civil engineering nanobots onto the embassy construction site.

The dispersed civil engineering nanobots, following a stored work program, initiated erosion at the location corresponding to the embassy building’s underground portion, carving a hole straight downward. Simultaneously, they constructed retaining walls from the material they had excavated, preventing the soil walls from collapsing, and continued the erosion process. Eventually, they formed the foundation floor and terminated their operation by self-destruction. Unneeded soil and groundwater were collected by the work craft, which made several往返 trips between the surface and the upper AA-0001, finally loading the last of the debris and ascending into the sky until they vanished from sight.

A pedestrian, pausing near the yellow police tape marking a restricted zone, blinked in confusion—first at the two spacecraft (general-purpose work vessels) descending from the sky, then at the memory that this vacant lot had been purchased by the Tokyo Metropolitan Government for use as an Agirakana Embassy.

When the hovering vessels seemed to disperse something into the air, two massive craters began forming in the field beyond the tape, as if the ground had been scorched by a blowtorch on expanded polystyrene. Onlookers stared, transfixed by the accelerated, special-effects-like transformation—then, slowly descending from above, a large object came into view. It settled perfectly into the newly formed holes, and suddenly, a building stood before them, its entire surface sheathed in dark gray smoked glass, like a shard of sky fallen to earth.

By then, a crowd had begun to gather around, people everywhere pointing smartphones at the spectacle—filming videos, snapping photos.

They were, in a sense, intimidated by the sheer technological prowess of Agirakana, only recently established diplomatic relations with the extraterrestrial nation whose vessel now stood before them—but more than that, they felt the tremor of history unfolding, standing right on the threshold of a world about to shift beyond recognition.

I watched the scene unfold on a monitor resting on the desk of my usual AA-0001 provisional Office, as I always did.

The fusion power plant had been no more than a matter of leveling the ground and digging drainage ditches—this time, just landing a vessel shaped like a building atop its foundation. The work, if one could call it that, amounted to digging a hole and reinforcing it. There was nothing to worry about. Nothing to do but watch, and wait.

The Embassy had been installed—completed, one might say—when the logistics terminal on the other side of the river was finished almost immediately afterward. A remarkably uneventful construction project, all things considered.

By nine in the morning, the work was done. Yet the onlookers gathered across the canal from the Sumida River, directly opposite the Embassy construction site, remained motionless, watching the Embassy like it might suddenly sprout wings.

The completed Embassy building was, in essence, a spacecraft. Its interior structure was no different from that of a ship designed for space travel. Even fully sealed from the outside world, air and water circulated and were recycled; energy was self-sustaining for decades. As for food, it consisted solely of nutrient paste—tubes of it—consumed by ordinary bio-noids, but even that was recycled and produced on-site. The implications of food recycling, one imagines, are self-evident.

As for energy, warships typically employ a combination of matter-antimatter annihilation generators—required for short bursts of high output—and multi-stage hydrogen-fusion generators. However, in this case, since the Embassy requires no high-power maneuvering during rapid transit, only a multi-stage fusion generator utilizing water as fuel has been adopted.

At that moment, airspace near the Senkaku Islands.

"This is P1-0019. Requesting response from Kanoya Base."

"Kanoya Base, reading you."

"Arrived at designated airspace. Commencing patrol duties."

"Kanoya, understood."

"Captain, they're definitely there. Looks like the People's Republic of China's Coast Guard. How many SS-3s (non-acoustic anti-submarine units) can you make out?"

"Radar shows twelve."

"Given the situation, coming all this way—don’t they find Agirakana at all intimidating?"

"Probably just came to observe, for now."

"Captain, it looks like it’s directly below us. Type 039A. SS-1 (acoustic anti-submarine officer) has confirmed a submarine beneath."

"Another submarine? They must be here to check on the coast guard's response."

"Looks like they’ll be crossing into the Senkaku waters any moment. Maria, contact the coast guard."

"This is Tako (tactical aviator)—confirmed the vessel group below as the People’s Republic of China Coast Guard. Likely to enter territorial waters within ten minutes. Submarine is definitely a 039A type, currently stationary at periscope depth."

"This is P1-0019, requesting response from Kagoya Base."

"This is Kagoya."

A group of vessels suspected to be from the Mainland Chinese Coast Guard and a single submarine have been detected near the Senkaku territorial waters. Approaching the vessel group for warning purposes.

"Kagoya, copy. …P1-0019, hold position for a moment. Just received a report from 'Kongo'. A flying object resembling a spacecraft has been detected 100 kilometers above the Senkaku area. Likely Agirakana. Disengage from the target and circle around—await further instructions."

"P1-0019, copy."

"Agirakana’s above us, it seems. Circling to observe. Don’t forget to log it."

"Captain, have Mainland Chinese fishing boats started flying lately? They’re off together, skyward now."

"Probably something Agirakana up to. Quite tragic, really. Meanwhile, what about the submarine below?"

"After rapid submergence, it appears to have altered course southwest. Will soon exit passive sonar range. Shall we deploy a sonobuoy?"

"No, that’d be a waste. You’ve recorded it, haven’t you? Send it to Kagawa right away. We’ll keep the patrol going."

"Where do you suppose those flying fishing boats are headed?"

"Who knows. Probably back to the port they came from."

Inside AA-0001’s temporary office.

"Let’s take a short break. Get me some tea."

The embassy’s construction—more precisely, its installation—was complete. I lounged in the temporary office, one hand cradling a mug containing a tea bag, while scanning news on the monitor.

"Here’s today’s noteworthy report. Multiple small vessels were reportedly seen flying through the sky—several ships navigating the Taiwan Strait allegedly witnessed airborne boats. Here’s footage shared online. They’re flying in neat formation, aren’t they? …"

And this photograph, also from the internet, allegedly comes from a fishing port along the mainland Chinese coast. Some claim the fishing boats lined up neatly along the dock were seen flying through the sky—though this has not been confirmed. To me, they look exactly like boats that were airborne. What do you make of it? ……

There was no one on the deck, I assume, but still—flying exposed at 1,000 meters above ground at 250 kilometers per hour must be terrifying. I suppose we’ve done a terrible thing to the crew, but perhaps they’ll just have to resign themselves to living in a particularly inconvenient country.

This time, the target was lifted by twelve towing beams, but as the number increases, standard work vessels reach their processing limits. Since numerous fishing vessels are currently approaching Japan’s EEZ along the Sea of Japan, we should have the support vessel construct dedicated work vessels sooner rather than later. Four should suffice—nothing combat-oriented, so they should be buildable in short order.

"Then I’ll leave it to you. If anything comes in like this time, please place it carefully atop the dock at the original port."

All vessels located between the Sea of Japan and the South China Sea are under surveillance. A courteous system has been developed by combining AIS (Automatic Identification System) data—emitted by ships themselves—with the requirement that every vessel, regardless of departure point, must return to its home port. Vessels that venture off course without an AIS transponder are also subject to the return system.

Since the crew configuration for P1 was unknown, I’ve assumed the number of personnel on P3C matches that of P1. The patrol flight was written based on a rough estimation.

“Flying at 250 kilometers per hour at an altitude of 1,000 meters” — that’s complete. Just a promotional bit for the Storage Officer. Those who’ve read that side of things will understand.