After parting from Chiyuri on the apartment floor below and returning to his empty home by himself, Haruyuki sat down on the living room sofa as soon as he changed out of his uniform, and ran his fingers over his virtual desktop.

He first opened a browser and vocally inputted the search words.

“Social camera, export.”

That news article on that was immediately displayed at the top of the search results.

[Installation of Japan’s security system into Hermes Cord]

‘Security system’ of course referred to the Social Camera technology.

And ?Hermes Cord? was—

The name of the ?space elevator? that had been built in the East Pacific Ocean.

Clicking the link with his finger, Haruyuki thought hard as he read the news story text.

This article reported, to summarize, that the same Social Camera Network as the one used in Japan was being adopted as the security system of the space elevator, an international facility. The ground station for the space elevator was located in the sea near Christmas Island, a place quite far away from Japan. With social cameras deployed at such a place, would the Brain Burst program really adopt it as an ?Area[1]?? Even if it did so, would there be a way to Dive there?

After desperately thinking over in his head for about thirty seconds, Haruyuki quickly abandoned the effort. He had too little knowledge to find the answer to this question. About Brain Burst, and also about the space elevator. At a time like this, he should ask for advice from his leader. Yes, if it was that person, she should have plenty of knowledge on both subjects.

After closing the browser and starting a mail, he then hesitated for a bit.

Haruyuki considered the ratio within himself between ?wanting to genuinely ask about it? and ?wanting to talk with her using that as an excuse?, and after concluding ‘Hmm, it’s a 6:4 ratio!’, he quickly threw himself into the text mail. In order to make an Dive Call appointment with the talented woman with zero weak subjects, one of the most senior players in Brain Burst, the head of ?Nega Nebulas?, and the ?Black King?, Kuroyukihime.

The specified time in the reply message he immediately got was in ten minutes. After finishing his supper of a frozen shrimp Doria dish and oolong tea in that interval, Haruyuki Full-Dived one minute before the specified time, and then changed the environmental data of his home’s local network to the object set he had downloaded from an overseas website.

When he had invited Kuroyukihime over to his home network in a similar manner once before, he had frantically flurried his head over the sets he had on hand that were either cold or filled with gunpowder, so since then he had collected ones here and there that seemed to have a good atmosphere. His mother had complained that he shouldn’t waste the storage capacity of their home server, though.

Once he had taken care of all the preparations, he pressed the connection request button as soon as the designated time arrived, and following a call sound for several seconds, an avatar appeared before him.

A jet-black dress with gleaming silver frills. A folded parasol of the same color. Black swallowtail butterfly wings with a red pattern design on her back.

With her mystique increased just a little more than her form in the real world, the fairy princess first smiled upon seeing Haruyuki’s pink pig avatar, and then looked around at her surroundings.

Then, her eyes suddenly widened, and she clung to the side of a pillar with great force while letting out a cry.

“U-Uwaah!?”

“Heh!? W-What’s wrong!?’

“E-E-Even if you ask what’s wrong, it’s all this! W-W-What-What is this environmental data!?”

When she shouted that, Haruyuki also frantically looked at the surroundings.

A ridgeline of mountains that hazily glowed purple. Vast woods and prairies, and a stone-made white city. The two of them were on top of a high, high tower that commanded a view of that beautiful scenery. Since there weren’t any handrails anywhere on the very narrow watchtower with a diameter of about three meters either and there were only two chairs along with a gas lamp in the center, the view was the best.

“U-Umm..isn’t it b-beautiful? It’s an object set I found beforehand in the German net, but..”

“Before that, just how many meters high is this thin tower!?”

Seeing her ask that with a pale face, Haruyuki peered down from the edge of the tower. His sense of distance told him the height from the ground was comparable to the height of the government office he had jumped down from in the duel earlier this evening, so he answered as such.

“E-Err..about five hundred meters..”

“That’s too high, idiot! Or what, were you aiming for some kind of suspension bridge effect!?”

“H-Huh? What is that?”

“The suspension bridge effect is..when in a dangerous place like a high suspension bridge, the feeling of fear is mistaken for..”[2]

Kuroyukihime stopped her words suddenly in the middle of her explanation, and after giving a light cough, she glared at Haruyuki again.

“..Anyway, that kind of psychological effect is already meaningless with me! Well..since this isn’t a duel, I’d probably be fine even if I fell from here, but at the very least tell me about this kind of thing in advance..”

After the end of her sentence dissolved into mutters, Kuroyukihime stood up at last, and then lowered herself down onto the chair next to her. After Haruyuki also sat down in front of her, he asked a little dejectedly.

“Umm, I’m sorry for scaring you..Should I change it to another object set?”

“No, it’s fine. Whatever the height, it’s something you searched for.”

Finally seeing a smile appear on her beautiful lips, Haruyuki let out a sigh. He scratched his head with his left hand that had turn into a round hoof, and then gave a delayed greeting.

“E-Err..Good evening, senpai. Sorry for calling you so suddenly.”

“Good evening, Haruyuki-kun. No, since we weren’t able to talk at school today, I’m glad I’m able to meet with you now.”

Since the cultural festival was at the end of June at Umesato Middle School and it was the last big job for the current student council, the vice-president Kuroyukihime continued to have busy days. Remembering that, Haruyuki took this opportunity to ask the question he had thought of several times until now.

“Speaking of which, why did you become a member of the student council, senpai? Since the chairman and vice-president are decided by election, you have to announce your candidacy, right?”

“Hmm, well yes. Your question of ‘Why did I, someone concerned with only becoming a Level 10 Burst Linker, do that?’ is quite natural. Duels that take up time in the middle of council meeting are also unavoidable, too.”

After giving a meaningful smile, Kuroyukihime continued.

“However, if I had to answer honestly, it was all because of Brain Burst that I became a student council member as well.”

“Eh..eeh!?”

“Think about it, to Burst Linkers, the school you attend is the most familiar and therefore the most dangerous field. To grasp all the information there and establish a firm footing could be called a rather indispensable matter. If you’re a member of the student council, you can have almost full access to the school database, after all. With that point of view..”

There, Kuroyukihime gazed at Haruyuki with a smile, and said something unexpected.

“I don’t think that the next student council elections that will be at the top for two terms will be a problem. How about you run for president, Haruyuki-kun?”

“Wha..W-W-W-W-Wha-Wha-Wha.”

After jumping up lightly out of his chair, Haruyuki shook his nose back and forth at high speed.

“I-I-I-I-Imp-Imp-Impossible! I-I-If I did something like that, I really would get a dismissal ticket by the Supreme Justice Court, really!”

“Hmm, then I suppose I can’t compromise by having Takumu-kun as the president and you as the vice-president either..”

“That! Isn’t! The problem!”

Resolutely turning her down while slightly infected by Frost Horn’s tone, Haruyuki forcibly changed the subject.

“Anyway, I dueled in Shinjuku today, and..”

“Yeah, I heard a rumor about it. It seems you fought desperately against some of ?Leonids? main forces.”

“N-News of that traveled quickly.”

When Haruyuki blinked at that, Kuroyukihime changed her smile into a slightly more sarcastic one.

“Of course I know that you were in quite a close mood with Chiyuri-kun.”

“N-No, that’s, umm, uh, err.”

“What’s wrong? I'm not really blaming you for anything, am I? The fact that my legion members work well together is most important.”

As he got a cold sweat from seeing her certain-kill Kuroyuki-smile, he changed the subject once again.

“J-Just before that duel ended, the opponent said ‘I’ll dropkick you from the Tokyo Sky Tree’, and then I suddenly thought of something!”

Quickly opening his browser, he called up the article in question and slid the window over to Kuroyukihime.

“Umm, senpai, do you also know about that news article?”

“..Japan’s security system in the Hermes Cord? Yeah, I feel like I glanced at it on the evening news, but..”

After glancing at the holo-window, Kuroyukihime looked up and tilted her head a little in puzzlement.

“What about this article?”

“Err..Actually, I had a little idea..although it may be something extremely off the point, but..or rather, I feel truly sorry about calling you out for something of that extent, but..”

After extending his mumbled excuses at high speed, Haruyuki finally brought up the main topic.

“That security system is the social camera technology, right? In other words, won’t the Pacific space elevator be entirely in the ?Camera Sphere?? When that happens..will the Hermes Cord appear in Accel World as well..is what I mean..”

When he had finished saying that much, Kuroyukihime widened her eyes, so Haruyuki prepared himself for her to laugh loudly and say ‘What stupid thing are you saying?’, or get angry and say ‘Don’t call me for such a foolish idea’.

However—.

“....H——mm.”

After giving a long hum, Kuroyukihime put her right hand’s fingers to her chin, and stared at the browser window again.

Finally, she raised her head and shook her head slightly.

“How to say this..you’re a guy who thinks of very wild things. But..it’s interesting. Yeah, it’s a very interesting idea..”

“H-Hah.”

As Haruyuki let out a foolish voice without knowing how to react, Kuroyukihime rose from her chair in front of Haruyuki and started walking back and forth on the narrow watchtower as if she had forgotten her fear of the five hundred meters height.

“Even if social cameras are installed there..it would normally be a closed network, but..in the Hermes Cord’s central station, is there really the extra space and spare electrical energy needed for accommodating a huge image processing system? Rather that that, it’s much more efficient and cheaper to process it by connecting to Japan’s SSSC through satellite connection. If it’s like that..then it’s possible that the BB Program[3]?could pass through even the firewalls there..”

“U-Umm.”

Somehow slipping in his voice there, Haruyuki vigorously waved both his short hands.

“Senpai, I don’t get what you’re saying at all.”

Stopping her walk at exactly that instant, Kuroyukihime’s right hand’s index finger waved back and forth as if she was wavering over how to explain, and then she spoke.

“Hmm..In other words, it’s like this. Since the Hermes Cord is a low orbit-type space elevator, its design is extremely tight..”

“What does low orbit-type mean?”

“..So that’s where you get stuck.”

Kuroyukihime gave a small wry smile, and sat back down on her chair again.

After giving a small cough, she called up a big blank window with her left hand. She drew a circle at the bottom of it with her fingertip, and wrote [Earth] inside it in elegant letters.

“Then, I’ll start from the big basics. A space elevator, or also called an orbital elevator, is simply put an incredibly high tower building from the surface of the earth up to space, in order to carry people and materials that use the elevator to go up and down it. Unlike launch-type rockets or round-trip shuttles, the elevator’s conveyance cost per weight can be made low beyond comparison. However..”

Kuroyukihime moved her finger, and drew an absurdly huge conical tower extending up from the round Earth.

“If, for example, they tried to build an elevator reaching up to space using the same method of construction as the Tokyo Sky Tree, the area of the base would have to be on a scale that would take up Japan’s entire surface, like so. No matter the circumstance, a tower of Babel like this is impossible to implement. So, you have to change your way of thinking.”

She quickly erased the tower, and this time drew a small square in a section of outer space far away from the Earth.

“First, you build a station in geostationary orbit 36,000 km away the Earth like this. Then, a tough yet lightweight cable is suspended down toward the Earth’s surface from there. The speed of an object that goes around geostationary orbit will synchronize almost perfectly with the Earth’s rotation, so it will seem to remain ?stationary? just as the name suggests without moving from that one point in the Earth’s sky. Therefore..”

She drew a line that went down from the square—from the geostationary orbital station to the Earth.

“Once the end of the cable that reaches the ground is fixed in place, a tower..or rather, a ladder that stretches up from Earth to space is completed in this manner.”

“Hah, I see!”

Haruyuki was impressed and struck his knee with his right hand’s hoof.

However, he soon after furrowed his eyebrows and turned his head sideways.

“No, but, wait a minute. No matter how light the materials are, if its length is no less than 36,000 km and it also has to be a thick enough cable for the elevator to be installed, its total weight will be incredibly huge, won’t it? By pulling tight on the cable, won’t the geostationary orbital station fall to Earth?”

“It will fall down!”

Since Kuroyukihime gave such an immediate answer, Haruyuki’s hips slipped on top of his chair.

“Wha..”

“Then, to deal with that, they do this.”

This time, Kuroyukihime extended a line upwards from the station, and then drew a black dot at the end of it.

“You just need to lengthen the cable further above the station and then stick a weight at its end, so that the station becomes the center point of the heavy weight..in other words, at center of its gravity. Then, an upward vector occurs due to the centrifugal force of the rotating weight, and it balances with the downward weight produced by the cable.”

“Hah, I see!”

Haruyuki was once again impressed, and then once again tilted his head.

“..So, where is that weight brought from?”

Kuroyukihime then gave a meaningful grin, and then used slightly abrupt words.

“—The concept of this ?geostationary orbit-type space elevator? was actually announced by America’s NASA forty-seven years ago, in 2000 AD. However, in those days, they predicted that it would take until 2062 to complete it.”

“Heh!? ..I-Isn’t that still much further in the future?”

“Yes. The reason why it was set in such a far future..is because, in NASA’s plan, it was planned for?an asteroid passing within Earth’s neighborhood to be caught, and then used as the weight fastened to the cable extending up from the geostationary orbital station.”

“Hah!? T-They were going to catch an asteroid!?”

“That’s right. They said that, if they waited for as long as sixty-two years, a handy asteroid would fly by with luck and they would also have developed the technology to catch it by then.”

“..That’s fifteen years from now, isn’t it? ....Isn’t it still impossible?”

“Yeah, it’s impossible.”

No longer able to understand anything, Haruyuki flapped his mouth open and closed.

“..B-But..The space elevator ?Hermes Cord? has already been built! If I remember right, it was complete five years ago, so that was in 2042. H-How did they make it then?”

“That’s the thing..”

Kuroyukihime answered while wiping away and erasing the diagram she had drawn on the window with her palm.

“It’s because, as opposed to the ?geostationary orbit-type space elevator? that I explained just now, which is so to speak an initial concept model, the Hermes Cord is a ?low orbit-type space elevator?, which was redesigned in a more realistic form.”

“Low orbit..type.”

“The basic idea is the same as the geostationary orbit-type. But the structure is different. The central station of the Hermes Cord floats at a much lower location than geostationary orbit, at 2000 km above the ground..Though that’s still outside the atmosphere.”

“Eh..err, if geostationary orbit is 36,000 km high..isn’t that unreasonably close to the ground!?”

“It is close. Since the cable is also much shorter at that height and can thereby be made lighter, the weight for establishing balance does not need to use something like an asteroid either.”

“A-Aah..I see..”

After nodding his head deeply, Haruyuki voiced a natural question.

“..Then, why didn’t they plan to use the low orbit-type from the beginning?”

“That’s because there’s a problem with it. A man-made object placed at low orbit..in other words, from 1500 to 2000 km above the ground, has to orbit at a speed that far surpasses the Earth’s rotation, in order to obtain the centrifugal force needed to balance the much greater attraction of gravity there than at geostationary orbit. For a geostationary orbit-type elevator, the lower end of the cable can be fixed onto the ground because the speed of its orbit synchronizes with the Earth’s rotation, but a low orbit-type cannot do that.”

While saying that, Kuroyukihime extended her finger and struck a small mark very close to the circle that represented the Earth.

“This is the Hermes Cord’s central station, built at an orbit of 2000 km high. A cable made out of entwined carbon nanotubes stretches out from it both above and below, and this cable is connected to a top station that acts as the weight attached to the top end and a bottom station attached to the bottom end.”

The bottom end of the line that extended upwards and downwards from the mark was just a little ways away from the outline of the Earth. Pointing at the gap between them with her finger, Kuroyukihime continued.

“This bottom station floats 150 km above the ground. If it was lower than that, the atmosphere would become too dense and the whole elevator would be drawn tight due to friction, and eventually fall to the ground.”

“Ha—....”

Letting out a long breath, Haruyuki spoke in order to put his thoughts in order while twitching his pig nose slightly.

“In other words..err, the Hermes Cord is an artificial satellite with a length of 4000 km that is connected to these three stations by a CNT cable..right? And this orbits the Earth at a much faster speed than the Earth’s own rotation..?”

“Exactly. Since the ground speed of the bottom stations reaches Mach 10, the low orbit-type elevator is also called by the nickname ?Hypersonic Skyhook?.”

“But then, what about..the fact that it was built in the sea near Christmas Island in the east Pacific Ocean? I have memories of looking at the huge man-made island on the news at the time, but..doesn’t the long tower surely extend up from there..?”

“That island is a base for the arrival and departure of space planes that carry people and materials to and from the bottom station of the Hermes Cord. The planes that take off from there rendezvous with the station at 150 km above and drop off cargo there. Then, the cargo is lifted up inside the elevator until it reaches the top station at 4000 km altitude, and then it is carried from there to a geostationary orbital station or the international base on the moon’s surface by a round-trip shuttle. Incidentally, since the geostationary orbital station is also right above the arrival-and-departure base, even if people say ?the Hermes Cord is in the east Pacific Ocean?, it’s not really incorrect.”

“Hofuu..”

Letting out a sigh for the nth time, Haruyuki looked at the window diagram anew. Since the Earth’s diameter was about 12,700 km long, comparing it with a 4000 km length could be considered as the same as the proportion between an apple and its stem, but the idea of such a thing flying overhead at Mach 10 was very difficult to take in.

“Hmm, somehow, I’m scared that it will fall due to some kind of rebound.”

When he murmured that without thinking, Kuroyukihime shrugged her shoulders lightly.

“Actually, there was someone who tried to make it fall as well.”

“H-Hah!?”

“What, you don’t know? From what I remember, there was a case at around the beginning of spring where a terrorist that had slipped in among some tourists tried to set a bomb in the central station. Due to that, it was decided that the Hermes Cord’s security system would be strengthened, and Japan was also participating in the bid for constructing the system, so it’s connected to the recent news about the first export of the social camera technology.”

“Uwah, so that’s how it was. I’m sorry, I haven’t been diligent with the news..”

Just like the times he was nominated to speak up in class and he couldn’t answer properly, Haruyuki hanged his head. However, Kuroyukihime didn’t scold him any further, and continued her explanation with a wry smile.

“The low orbit-type elevator Hermes Cord has a small and thin cable compared to that of a geostationary orbit-type. Its design is tight. That’s why, even if a bomb of a size that could fit in a pocket went off, it could cause tremendous damage depending on the location of the explosion. There is also no spare electric power or space for accommodating a large-scale surveillance system in it. I think that is the reason they adopted Japan’s social camera technology..Yeah, with this we can finally return to our original conversation.”

Letting out a long breath, Kuroyukihime waved her right hand’s fingers and opened up the VR operating menu. She materialized two glasses and presented one of them to Haruyuki.

‘Damn it, I should have prepared something like that as the one that called her here!’ Despite inwardly panicking like that, he accepted it and took a sip. Seeming to be an original drink that had had countless flavor parameters fine-tuned, it was unlike any drink in the real world, and yet a fresh bittersweetness without any unnatural quality to it spread throughout his taste buds.

“It’s..It’s very delicious.”

When he said that, Kuroyukihime gave a small smile and then nimbly extended out her avatar’s left hand.

“I’ve also recently been doing real cooking practice, but..A task that you can’t just do over again is really troublesome. Did you know, Haruyuki-kun, light-coloured soy sauce’s only difference is its lighter color! What’s with that, is it supposed to be like salt water!?”

“H-Heh, I didn’t know that..Or rather, why are you suddenly trying to raise your cooking skills..?”

“That’s obvious, it’s so that, one day, for yo..”

Suddenly closing her mouth at that point, Kuroyukihime gave a big cough.

“..It’s just for recreation[4]. More importantly, let’s finally get back onto the main subject.”

Following her slightly forceful change of topic, she continued her rapid-speech explanation.

“I said that the Hermes Cord doesn’t have the room to accommodate a large-scale surveillance system as well. So it became the turn of Japan’s social cameras. That system collects in one place the images photographed by countless cameras through an exclusive high-speed network, and signs of criminal activity are detected by automatically analyzing them with a super high spec supercomputer. For example, if a gun were detected by a camera somewhere, the system would immediately analyze where the person who has that gun is and where they came from, and then continue tracking where they go. The locations of the facilities where this processing is performed, the ?Social Security Surveillance Centers?, have not all been revealed to the public.”

“E-Even you don’t know, senpai?”

When Haruyuki seriously asked that, Kuroyukihime gave the greatest wry smile yet.

“Hey, just what do you think I am? I’m only a frail female middle school student, there’s no way I would know the greatest of our nation’s state secrets such as that! ..Well, I do have some guesses, though.”

“W-Where!?”

“That’s a secret..More importantly, just as I explained just now, the social cameras gather the automated image analysis that acts as the guts of the system at the SSSC and process it there. In other words, neither huge recording equipment nor human operators are required for the surveillance cameras usually. Supposing that that very ?simplicity? is the reason it was adopted for the Hermes Cord in this case..you could say it’s inevitable that the space elevator’s cameras and Japan’s social camera network are linked.”

*POKAAN*?As Haruyuki was listening attentively to these words, Kuroyukihime gave a wink as she said the word ‘connected’ as if she were waiting for something, and then Haruyuki finally remembered the main purpose of this sudden Dive Call.

“Ah..I see, err, so the fact that they’re connected means, in other words, umm..”

While flapping his pig avatar’s short arms, he shouted,

“..we can go there!? To the Hermes Cord in Accel World!!”

“Hmm..Well, we’re only at the stage where we can’t say it’s impossible yet, though.”

Giving a mischievous smile, Kuroyukihime continued in a tone as if she was somehow testing something out.

“First, there is the question of whether Brain Burst, a dueling game, will faithfully extend its stage all the way to there. And even if the networks are connected, how would we go all the way there? We Burst Linkers, generally, Dive in at the places where our real bodies are. In other words, in order to go to the Hermes Cord in Accel World, it would be necessary to actually board the space elevator on this side. Tour packs for going up to the geostationary orbital station have also been put on the market these days, but it’s expensive.”

“..They’re super-expensive, aren’t they..”

Haruyuki dropped his shoulders. He considered for an instant that as Silver Crow, with his wings, he could fly up to the bottom stations above after Diving on the ground, but he dismissed the idea before even voicing it. The limit to the altitude Crow could reach was at most 1500 meters. On the other hand, Hermes Cord floated in the sky a hundred times higher than that, at least 150,000 meters high.

No, before that, he couldn’t even go to Christmas Island, the terrestrial space plane departure base, with a middle school student’s pocket money at all.

“Hmm..so in other words, unless you’re a super-rich kid, there’s no way to Dive in at the Hermes Cord..”

“Or rather, if you could go to the actual thing in the real word, I don’t think there’d be any need to go through the trouble to Dive into the reconstructed article in Accel World.”

“That’s..true.”

*HAFU*?Giving a sigh of disappointment this time instead of admiration, Haruyuki looked up at the sky.

Even when seen from the top of a 500 meter tall tower, the virtual blue sky seemed as if it were far away and went on forever. No, in such a VR Object Set that’s freely distributed to the public, the ?sky? would not reach higher than 10, or maybe 100 times the height of this tower. That was because there was nothing ?beyond? this blue sky. This was a closed world, where nothing but the thin blue color continued on past it.

“..Haruyuki-kun.”

Hearing his name suddenly called, he turned his face back down, and met his gaze with Kuroyukihime’s gentle yet somehow mysterious-seeming eyes.

“Why do you want to go to the Hermes Cord so much? Compared to how you can fly freely with your wings, the space elevator is only a man-made object that goes around a decided orbit, after all.”

“Eh..err.”

Having been thrown an unexpected question, it took several seconds for Haruyuki to form the ambiguous thoughts inside him into words.

“Umm, of course, there’s the reason that I simply like high places as well, but..also, I was thinking that, supposing it was possible to go there, that person’s wish might be fulfilled even just a little. That person..who has always aimed for Accel World’s sky, no, for ?beyond it?.”

The instant she heard that—.

Kuroyukihime’s eyes widened slightly, and then her eyelashes turned down.

The words that eventually came out of her lips-->>

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