“Hahaha, damn! This guy really does go up and doesn’t stop. Y’all keeping up with ‘em?”
“Naturally. But this plasma shower’s something else. It feels like the radiation shielding needs some adjustment.”
“Keep going, I’ll figure something out for you.”
“Low pressure, temperature’s 700°C… the atmosphere here’s pretty interesting… the sensors are burning to a crisp one after another; it’s like I can’t keep any control. What a pain.”
“It’s not ‘interesting’, you’re making mistakes and they’re spiraling out of control. Do you even know how to deal with control surface damage?”
“Don’t get pissy with me, no one’s getting this far unless they know what they’re doing.”
Ferocious, carnivorous fish dragged red lights in tow as they danced madly in the folds of blue and purple light draped over the polar region. Those extraordinary fish were clever, capable of changing course at will, and channeled enough energy to power a city, but tonight they had to move with a little less grace.
“Our catch is trying to make a break towards the star. Florina—tch.”
“My, it seems another head escapes you. Don’t fault your wife, will you?”
“And just who are you talking to? My wife’s doing great, so shove off.”
Once again, a vessel lost its prey in the dazzle of the polar night’s unsetting star and needed to start from the beginning, searching the abyss for another target. The environment, besshu, and the boat’s performance itself were all more unforgiving than usual, and it was proving to be tough fishing for the skilled anglers.
Moreover, broadcasting their voices beyond their boats while they fished wasn’t the usual way of things, but the proud, talented people who had gathered couldn’t help but trade pointed barbs with a mix of confidence and bravado. Naturally, their roasting one another created an unusually biting atmosphere.
Inside that atmosphere, Terra and Diode—ignoring their rivals’ competition to improve their catch—simply repeated their ascents and descents.
“Terra-san, I’m turning power over to you, is that okay?”
“Yeah.”
“Beginning the fourth net.”
They started to descend from the altocumulus cloud tops towards a target deep in the abyss. They dived below the besshu, which was beginning its ascent, then turned in pursuit and approached its ventral side with a scissor manuever. The two were reenacting the traditional approach by imitating Meika’s technique.
“We’re keeping pace… so we’re putting out enough power. We may even have some reserve this time?”
Diode calmly touched the throttle. Behind her, Terra quietly monitored a swarm of VUI panels.
“I guess we do, but we’re still doing the same thing as before. We’ve only put the pieces we need to get started together.”
She expanded two panels. Displayed were detailed images of a tubular body making a vertical ascent. The alien creature’s flight was peculiar, bathing in the oblique light as it rhythmically twisted and turned. Terra felt like she sensed a certain desire, strangely familiar and earnest, from the 65-meter-long, 16,000-tonne body of the besshu as it climbed up an auroral fold.
“The only difference is that I can focus now that we came prepared with the outboard circuit, anti-glare fishfinder, and protective shielding for the combustion chambers, but that’s not enough.”
“Well, we’re doing a hundred times better than those guys, who don’t have any of it.”
Diode quickly peeked down. Twenty kilometers below, she was able to watch a point of light fail its approach during the ascent and helplessly fall away. She didn’t see any humor in it—that had been them last time, and had it not been for Meika’s advice, they wouldn’t have been able to climb out again back then.
She was struck by a sudden thought—how did Meika feel about what Nurude was doing? Both Meika and her father wanted to get their hands on her and Terra, but for different reasons. There was no way Meika, who only craved a specific kind of love, wanted the authority and triumphalism that Nurude did—so, what did she feel as she flew?
As Diode pondered that, something happened to catch her attention from the corner of her eye. A lone pillar boat, much higher in the sky than they were, danced wildly as it caught up to a nishikigoi and covered it from the head down with a rotating crossarm. After the successful catch, it followed a low arc back to level flight.
A black flower icon crowned the aircraft on the boating system's navigation display.
“Meika caught–”
“Closer, please!”
Diode felt the sharp voice slap her from behind and refocused on the task at hand. With a mere adjustment of trim, she brought the boat in line with the besshu fifty meters ahead. Now she worked for the sake of a person who was far more important than someone who wasn’t there; she worked for Terra’s sake. Her piloting skills were usually Terra’s main priority, but she had to put them on hold because—
“Ugh, this particle density is super high… How does the besshu not get killed by this? Or is this not able to kill it?”
Terra was talking to herself. She wasn’t trying to get Diode’s attention, the topic just bothered her that much. Diode was currently focused on delicately maneuvering the boat closer to the besshu; in her own control pit, Terra studied twelve VUI panels arrayed in three columns of four. Several of them were sensors that carefully examined their prey—a thermometer, a fluid motion speedometer, and active and passive sensors that used everything from radio up to x-rays. There was also a gravimeter, but this tool served a totally different purpose from the others.
“Even though I know there’s something going on inside, I just can’t tell what it is…!!!”
The high-altitude atmosphere as they ascended splashed with blue. Terra placed a marker near their prey’s wide-open mouth.
In a quiet voice, Diode shyly spoke up. “That network of blood vessels was for cooling down… was it not?”
“A normal rete mirable isn’t for cooling down, it's for warming up.” Terra spoke in a low, controlled tone that Diode rarely heard her use. “Even though the environment up here means the besshu needs to cool itself down, the rete mirabile doesn’t seem like it’s arranged for that! Something’s off, but what’s off is…!”
As the sound of Terra’s agonizing continued behind her, Diode tried to remember what she’d heard back in Table of Johor’s decomp lab.
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“I’d think it’s a rete mirabile, judging from the structure.”
That was the first thing the male researcher had said.
Projected on the laboratory’s data table was a structure composed of an intricate web of thin vessels divided into red and blue colors. Diode thought it was a placenta or something like it at first, but it turned out to be an entirely different organ once the researcher launched into his explanation.
“What we call the rete mirabile is a net of blood vessels found in certain animals. Animals developed circulatory systems as they evolved, with part of a pulse pushing blood to the extremities and another part receiving it from the core. Sometimes those form a tangled network of veins and arteries near their core, which is the aforementioned rete mirable. This net is capable of regulating body temperature by warming up the very cold venous blood before it returns to the heart and cooling down the very warm arterial blood before it reaches the brain.”
“So it’s not a placenta, it’s a kettle…?”
The researcher picked up on Diode’s whisper and nodded. “That’s correct. The rete mirabile is a heat exchanger built from blood vessels.”
“Ahhh, I remember now! Back on Earth during the Anno Domini era. That was something that was inside the marlins, wasn’t it?” Terra asked.
The researcher confirmed her with a nod. “That’s right. Other animals, like sharks, giraffes, and the red gulguiuli also have it, but maybe it is closer to a marlin’s in this case. Marlins were fish capable of swimming insanely fast, and it was the net that enabled them to do so. The organ warmed up the blood from the parts in contact with cold ocean water, which allowed it to maintain its muscular functions despite being cold-blooded.”
“A very well-balanced animal, huh?”
“Every living being is. Even the nishikigoi. If we’re being precise, it has two independent circulatory systems, and they only make contact through the rete mirabile. It’s a multi-step heat exchanger, or, well… actually, it just seems like a heat exchanger…” The researcher, who had spoken smoothly to that point, abruptly faltered. “The truth is, it’s a huge mystery.”
“A mystery?”
“This isn’t really a rete mirabile,” the researcher suddenly said an odd thing. “It’s shaped like one, but there’s no way this organ is one.”
“What do you mean?”
“Marlins swam in cold ocean waters, but this besshu—this nishikigoi—flies in 700°C skies over a gas giant. There’s no need to warm up its insides, so what use does it have for a heat exchange organ? You wouldn’t happen to have any guesses, would you?”
Terra tilted her head, her interest caught. “What about the other way around, for cooling down?”
“Heat can be produced with fuel, but you can’t produce cold. We’re certain the heat is reaching the body’s core immediately, so a heat exchange organ loses the exchange differential. What else would it exchange?”
“Hmm, you’re right. Just what is this…?”
“Right?! It’s a total mystery!” The researcher rested his elbows on the data table and clutched his head. “It melted right after dissection, so its composition and substructures are also a mystery. I think the structure might be self-destructing… but so it goes with besshu research. We’re always finding mysteries big and small without generating a lead on the biggest mystery of them all.”
“The biggest?”
“How did besshu, which closely resemble Earth animals, appear in a gas giant?!”
“Ah, yeah…”
For better or worse, they weren’t in a situation where they could break their brains thinking about it, so Terra kept her mouth shut and smiled to move along.
“Seriously… out of our hands.”
After a short silence, Diode spoke up from the sidelines. “Still, since the nishikigoi has this organ, doesn’t that at least mean it serves some purpose?”
Like buddies, Terra and the researcher shrugged at the same time and looked down at Diode.
“We’d like that to be the case, but there’s no guarantee it serves a purpose. See, animal morphology isn’t always necessarily best adapted to its habitat, and there are plenty of situations where they manage to make do one way or another by continuing to use and adjust the organs and abilities they, by chance, already had.”
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As she remembered that exchange from a few days earlier, Diode spoke up. Her voice didn’t make it far from her mouth. “So, this might be pointless after all…”
Just as she said that, the close-up of the besshu’s ventral area began to move. More accurately, Diode had the acute sense that there was a sign—not much more than a feeling—that its posture had changed.
They quickly put the rotating crossarm into action and swung the net over the besshu’s head, even though they knew the odds of it working were slim. Their approach didn’t have the necessary precision—not that they had sucessfully managed that even once to begin with. And at this point, they were aware covering its head would trigger its next move.
The colossal fish twisted its body. Diode immediately pushed the thrusters on one side of the boat to full throttle and avoided a smack from the half-open fin of the explosively accelerating besshu. Naturally, in exchange for evading it, their own positioning collapsed.
Terra screamed. “Argh! Why do you have to be so… so contrarian!”
“Sorry.”
“No, not you! I wasn’t saying that to you, Die-san! I meant it abou–”
“Our fate rests on this uncooperative thing and the Gendō.”
“Exactly!”
The pillar boat was falling on its back end. Another besshu began to climb with a burst of power, and as Diode watched on, she heard a stubborn voice in her ears.
“Die-san, let’s start the fifth net!”
“...May I ask you something?” Diode asked after rolling the boat and making surface stability adjustments to slow their descent.
“Sure, what is it?” Terra replied.
“It’s likely that unless we’re in precise, supersonic flight with less than a 90cm margin of error, we won’t be able to catch the nishikigoi. Assuming the traditional Gendō fishing method is the only way to catch it, and that this has no relationship to that mysterious organ, and that we’ve been attempting all the wrong things—then what should we do? Should we switch to the Gendō way of doing this from now on?”
The pit behind her fell quiet. Diode looked down at the sea of clouds below, checked the gauges on the VUI, looked out across the sky, and then looked below again. She found one, two… five potential targets, then started to feel like she was about to suffocate.
She might have pushed too hard. Forcing a conclusion like that on her partner, who had been desperately trying to act tough, might have crushed her motivation. And if she really had, then her partner was probably dejected, weakly withdrawing into her giant body and tearing up behind Diode’s back—as had happened many times to this point.
If that’s the case, I’ll have to scold her again—which is a pain, frankly—but getting her motivated again is a must or we’re not getting out of this.
Diode steeled herself and took a single deep breath before turning around. “Terra-san!”
“Ah, sorry, give me a moment.”
“...Huh?”
Diode was taken aback. A single huge VUI panel was projected in the seat behind her, and a large number of blue, green, yellow, and red arrows illustrated the complex flow around a 3D model of a besshu. Terra, who Diode could see with just a glance was in the middle of a scuffle between data processing and a very intensive simulation panel, was laughing. To describe it exactly, her cheeks were flushed, her gleaming eyes blazed, and the shape of her smile was strange. The sight of her laughing by herself was just the kind of thing that would make others very hesitant to come near her. Diode recoiled.
“Woah.”
“This… this is probably it. Can you believe it? Can you believe that organ is not only this efficient, it can even sense the electric field too? Being able to make calculations ahead of time is practically a miracle, isn’t it?! Like, didn’t it feel like we reached the ‘so it all comes down to this, huh’ point here?!”
“Sorry, but I didn’t catch a word of that. Also, your face is scaring me.”
“What, I’m scaring you?” Terra hurriedly massaged her cheeks with both hands and smiled weakly. “Is this better? …Anyway, you were saying?”
“Nothing…” Diode shook her head and put everything into an emergency smile before bowing her head. “Sorry, looks like I still didn’t fully believe in you. You’re awesome.”
“Huh?”
“Nothing, please keep going. What about our course, then?”
“What? Oh, right! So, for our next target, please chase it slowly!”
“Is it really okay to go slow?”
Diode tried to double-check that she’d heard correctly, and Terra confirmed again that she’d handle it somehow.
“In the meantime I’m going to be decomping!”
“...Into what shape?”
“We’re keeping the same shape. I’m copying that organ—no, I’m going to make it digest!”
“Digest?”
“Yeah!” Terra’s blonde, wheat-colored hair gently drifted in the gel from her outpouring of excitement. She spoke in gestures.
“We’re going to digest the wind and light up here and fly away while we spin! …That’s a really sloppy description, huh? Okay, so I can explain properly–”
“It’s fine.” Diode’s heartbeat quickened, already sensing again both the admiration and astonishment she had savoured so many times before. “It’s fine, you don’t have to say it. Show me everything and don’t hold back.”