"Fusion reactor operating stably. Output voltage at rated levels. Capacitor input and output stabilized."

“It’s finally happening…”

The microwave power transmission system, installed at the apex of The Tree Fortress, was about to begin full-scale operation.

While primarily a test model, the system’s main objective was to identify potential issues. Once operational experience had been gained, a larger transmission facility would be constructed at the fortress site on the northern continent.

"Initiating microwave power transmission."

The initial recipient of the transmission was Alpha-Class Destroyer No. 18, Romeo, stationed nearby. Equipped with a microwave receiver, the test would assess whether power could be successfully transmitted and whether any environmental impacts would occur.

"Transmitter voltage at specified levels."
“Commander, the sea surface…”

“Oh…”

The eldest android sister, Akane, noticed a slight increase in the sea surface temperature around Romeo, the target of the microwave transmission.

“The dispersed microwave energy is heating the sea.”

“Is the beam focus insufficient?”

As they exchanged observations, the Romeo crew signaled that their receiving equipment was ready.

"Romeo receiver voltage stabilized. Initiating power supply to onboard systems."

Simultaneously, the ship’s gas turbine generator was disconnected from its power grid, and the microwave receiver was activated. In theory, the transmitted power should fully meet the ship’s energy demands.

"Shipboard voltage stable. Receiving equipment operating without issues."
“It’s a success so far.”

“Yes, Commander.”

The microwave transmission itself was successful, though there remained an issue with low coherence in the transmitted waves. Theoretically, power could now be transmitted indirectly within a 10 km radius of The Tree Fortress.

However, the environmental effects of such high-powered microwaves, including sea surface heating, raised concerns about efficiency and sustainability.

“This is likely the limit for the basic transmission system in our current tech tree.”

“Olive is working on improvements to the microwave system, right?”

“Yes, Commander. She’s finalizing tests on technology that synchronizes multiple transmitters to direct power to specific points. While the system at The Tree Fortress transmits power linearly, the new technology leverages spatial coherence to transmit power to any point within range. With proper transmitter deployment, it could bypass obstacles entirely.”

One of the major limitations of the current microwave power system was that any obstacles between the transmitter and receiver would disrupt the transmission. This made the system impractical for land use and restricted it to open air or marine environments.

If Olive’s research succeeded, this limitation could be overcome. Known for her passion for innovation, the humanoid android was already achieving consistent results in her lab and was preparing to test the technology on external installations.

“We’ve also begun releasing inventory reserves now that resource procurement is stabilizing. I’ll have updates on those results soon.”

“That’s exciting. And the relay drones—those are progressing too, right?”

“Yes, Commander. Microwave relay drones capable of operating at altitudes of 20–30 km for several years are in production. With no aerial obstacles at those heights, even a small number of drones could cover vast areas. Once fully operational, they’ll greatly expand the activity range of our equipment.”

Currently, the bottleneck for The Tree Fortress lay in fuel consumption.

While resources were being steadily secured through trade with Telek Harbor, the operational fortress under construction would soon allow for self-sufficient resource extraction.

The problem was the lack of a viable fuel alternative to petroleum—and no petroleum deposits had been discovered yet.

“Really, though. We need to keep searching for petroleum, but at least we now have electricity as an option. Microwave power won’t work for long-range operations yet, so we’ll still rely on petroleum for now.”

“Yes, Commander. If rare metals become more accessible, we’ll be able to produce high-performance batteries, but until then, petroleum remains necessary.”

Survey missions conducted by the Albatross reconnaissance aircraft were steadily expanding their search radius. However, as the range increased, so did the time required for exploration.

Finding convenient surface-level oil deposits seemed unlikely, so the focus remained on mapping underground geological formations likely to contain reserves. The library provided data on favorable subsurface structures, which guided the exploration process.

“If we operate within the power transmission range, petroleum becomes unnecessary. For now, this includes The Tree Fortress, the second fortress, Telek Harbor, and Iron Town. Most of our activity is concentrated here, which should significantly reduce petroleum consumption. We can redirect resources to long-range exploration.”

“Yes, Commander. However, we’ll soon need to consider the actions of other nations. Expanding the search radius will inevitably lead to border violations.”

“Oh, right. That’s another issue…”

Akane interjected hesitantly.

“The arrow… that letter…”

Her interest in the multilingual arrow message had previously led her to translate its contents. Though not truly decoding the message—since it included Afrazia’s local dialect, which she already understood—Akane had been intrigued by its implications.

“Yes, Akane. That letter came from someone affiliated with the Forest Nation of Rebresta. If we take it at face value, it was sent by their border patrol.”

“Commander, I’d like to pursue negotiations with Rebresta.”

For Akane, who rarely showed interest in anything beyond books, this was an unusual request. Clearly, Rebresta had captured her curiosity.

“Hmm… It’s not something we can act on immediately…”

The Commander wanted to grant her sister’s wish but faced logistical hurdles. Sending Akane herself was out of the question, and deploying machines was complicated by the distance, which made both communication and energy supply challenging.

“Commander, if relay drones are deployed strategically, it would eventually be possible to send machines to Rebresta. For now, communication might be the best option.”

This issue was also on <Ringo>’s radar. Establishing a power grid with relay drones and microwave transmission would enable The Tree Fortress to deploy mechanical units to distant locations.

Initially, these would likely be small reconnaissance units, but even that would be a significant improvement over the current inaction. Eventually, inland bases could be established, with power and transmission facilities extending the activity range exponentially.

“The material costs will be enormous…”

Looking over <Ringo>’s proposed plan, the Commander sighed. Existing resources wouldn’t suffice, so simultaneous exploration and extraction efforts were necessary.

“If we gather enough resources, maybe I’ll divert some toward space development.”

“Yes, Commander. That plan is already being drafted.”

Relay drones were relatively low-cost and easy to deploy, but they were limited to atmospheric operation. Their altitude cap was around 20 km, and their coverage area was limited.

A system placed in satellite orbit, however, could eliminate these limitations. At an altitude of approximately 400 km, a solar power station could be established at points like the Lagrange Points, producing massive amounts of energy efficiently and safely.

“Well, that’s still a pipe dream for now…”

Space development presented its own set of challenges. First, a rocket launch platform would need to be built offshore, requiring vast amounts of concrete and steel.

Then, rockets and rocket fuel would need to be developed, ideally leading to reusable spacecraft. Once stable, projects like an orbital elevator or mass driver could be pursued.

“Commander, for now, focus on the second fortress construction and nearby resource extraction. Let’s leave space exploration for later.”

“…Oh, right.”

Gently nudging her back on track, <Ringo> reminded the Commander of the current priority: the second fortress and the microwave power transmission system.

“Right. For now, let’s focus on leveling up. First goal—securing a ton of resources.”