But you could say the same thing about me, still in my school uniform since I’d stopped in on my way home from school. The reason why I, Kazuto Kirigaya, was here—the laboratory of a start-up in Roppongi, Minato Ward—was simple. It was just a part-time job.
Full-dive devices, evolving from the first generation of large amusement machines, into the second generation of NerveGear and AmuSphere, and then into the third generation of the medical device Medicuboid, obviously did not choose their users, but there was a certain level of so-called compatibility with them. In other words, it was a matter of how effectively the brain could connect with the machine. There was some native aptitude, but this could also be improved through long hours of dive experience.
And the people in Japan—no, the entire world—who currently had the most dive hours were without a doubt the survivors of the SAO Incident of a year and a half ago.
In this fourth-generation machine developed under the lead of Takeru Higa, the level of precision in the connection with the brain was overwhelmingly greater than any previous machine, but apparently, those high specs had brought about unexpected issues. Because the amount of information exchanged between the brain and the machine was so large, when the entire staff, including Higa, did test dives to try and get data, they couldn’t move sufficiently inside because of “VR sickness.”
Thus, Higa used a certain line to hire me, one of the survivors, to work part-time as a test diver, and blinded by the rate of hourly pay, I came out here to Roppongi.
“So anyway, I do a full dive and then just move around all over inside. Is that it?” I confirmed, stroking the cool aluminum exterior.
“Right, exactly.” Higa bobbed his head up and down in agreement. “It’s pathetic, but the instant we see the graphics inside, we’re practically barfing. We’re developing a structure right now to regulate the depth of the connection in line with the diver’s aptitude, but to make that, someone has to dive and get data, you know? Ha-ha-ha!”
“Well, you’re paying me, so I’ll do whatever you want. But before I do, let me just make sure of one thing.” I glanced at the imposing headgear interface before continuing. “Um, diving with this is not actually dangerous…right?”
“Of course not! Of course it’s not! Of course not!” Higa said three times, and nodded deeply. “You’re an SAO survivor, Kirigaya, so I totally get that you’re worried. It’s fine. The danger posed by the machine I developed is only the tiniest, seriously tiniest, bit!”
“It is? That makes me feel bet—” I swallowed the end of my sentence and looked at Higa again. “‘Only the seriously tiniest bit’?”
“No, no, no! It’s fine! Totally fine! It’s seriously fine!” After saying each part three times more, Higa continued quickly in a low voice, “It’s just, if the power suddenly goes out when you’re in the dive, it’s a little…you know…”
“What do you mean, ‘you know’?”
“No, no, no problem! We’re all set up with two types of backup power supply and an emergency battery!”
“What comes after ‘you know’?”
“No, no, no, no problem! No real damage! It’s just, well, a little, like…” Higa’s eyes darted around behind his round glasses, and I took a step toward him and stared hard. “Like, it’s, well, a little nondigital phenomenon…”
“What does that mean?”
“Basically, not logical…or maybe not natural…To put it bluntly, this,” Higa said, and dangled both hands loosely in front of his chest.
With this gesture, I finally got what the scientist in front of me was saying. “Huh…? Gh-ghosts…?”
Faced with a gaze that said, What is this guy on about? Higa shook his head quickly once again. “No, seriously—for serious, Kirigaya! I totally saw one, clear as day! Listen. As you can see, this test machine is still the only one in existence in this world. And the number of people who can dive at the same time is one. And yet…staff members who’ve dived into the test field saw a hazy human shadow more than once inside,” Higa said, with a look on his face like, if this were a manga, there would have been small queasiness effect lines on his forehead.
A smile rose up onto my own face, interfering with my brief foray into seriousness, and I shrugged exaggeratedly. “Couldn’t it have just been that they saw some kind of light effect because of the VR sickness? Or maybe there’s a bug in the shader—”
“Non! There’s no way any program put together by the génie Higa would have such a pathetic bug!”
I ignored the sudden slip into a foreign language and moved my shoulders once more. “I mean, okay, if they’re showing up in this room, that’s one thing, but ghosts appearing in a VR world—I’ve never…Okay, I have heard of that, but when I tried to verify rumors like this in Aincrad, it wasn’t a ghost or anything, it was an NPC.”
This, of course, was Yui, the top-down AI existing even now as my and Asuna’s “daughter.” Although if I told her that we first went looking for a ghost or something, she’d probably get mad.
“In other words, everything you can see on the other side is digital code, so their existence should be properly noted somewhere in the memory address. If you look into the time logs, you should be able to find out soon enough what the test divers saw,” I pointed out.
Higa pursed his lips like a child. “Of course; I checked those. But there was rien in the logs. In other words, it’s a fact that this phenomenon is not an object generated by the hardware or the software of the test machine. So it’s really a ghost…or…”
“Or?”
“…Look, this is something I shouldn’t actually be telling you. So I’d like you to pretend you never heard it.” After this showy preamble, Higa lowered his voice and continued, “The heart of this test machine incorporates quantum calculation circuits. In other words, a quantum computer.”
“…Did you make that, too, Higa?”
“I’d like to say oui, but unfortunately, the basic theory was crunched out by Kayaba. Well, at any rate, it’s been said for a long time that a quantum computer might possibly interact with parallel worlds. In the world of science fiction.”
“P-parallel worlds?! You seriously believe in that?” His way of speaking was slipping into my speech.
Higa moved his head in an unreadable motion that was half-assenting, half-negating. “Only on the level that something like that would be great! But, you know, if it is true, that would explain the ghost problem. In other words, if this test machine interfaced with another quantum computer in another time stream…the past or the future or a parallel world, you’d be able to see the shadow of a diver who shouldn’t be there.”
“There’s not too much difference between that story and a real ghost, you know.” I shrugged again before glancing up at the clock on the wall. “Well, I guess I’ll see if there’s a ghost or not when I dive. My little sister’s apparently cooking something today. If I don’t make it home for dinner, she’ll knock me into next week, so let’s just do this—”
“What? You have a little sister? H-how old is she now?!”
Feeling a curious déjà-vu at Higa’s reaction, I ignored the question and sat down on the bed of the test machine. I aligned my body with the indentations, and slid my head beneath the headgear. “Okay, I’m ready anytime.”
I urged Higa, who had a thwarted look on his face, and closed my eyes. Over the sound of the motor lowering the headgear, the final explanation reached my ears.
“Okay, I’m starting the connection. Your avatar’ll be generated automatically from your self-image, Kirigaya, so you shouldn’t feel any weirdness.”
“Got it.”
I raised the thumb of my left hand, and as if in response to that, the test machine behind me started to hum quietly.
There it is again.
Sensing his world shake strangely, Haruyuki Arita narrowed the eyes of his pink pig avatar.
The world was frozen a uniform transparent blue. The initial acceleration space, a blue holding-zone world
where he could dive with the “burst link” command. In the depths of his Neurolinker—a quantum communication device equipped on the neck of the Haruyuki in the real world—the mysterious application named Brain Burst had been installed. In response to Haruyuki’s command, the BB program accelerated his thoughts by a thousand and made him do a full dive into this field dyed blue.
The blue world existed so that players could search the matching list to find a duel opponent or to launch external apps and do all kinds of tasks. The reason Haruyuki was currently accelerated was the latter. In other words, to finish up the homework that was due to be submitted that day. More precisely, his remaining extension was only another fifteen minutes in real-world time. Not only did the report homework given in fifth period Japanese History slip out of the realm of memory in his brain, he had even forgotten to mark it in his schedule app.
If it had been math or English, he would have had the last-resort option of asking Takumu or Chiyuri to let him copy—although they would certainly make him pay them back double later—but that wouldn’t work with an essay-style report. Thus, he had used a precious burst point to accelerate and was single-mindedly typing at his holokeyboard.
But when he sensed a strange aura and lifted his head, it seemed like the center of the blue classroom projected in his vision, devoid of people, flickered lazily.
“What was that?” He got up from his seat in his avatar body. When he took a few steps forward among the rows of desks and strained his eyes, he saw a faint ripple again on part of the blackboard. Right, it was almost like there was a transparent something between Haruyuki and the blackboard.
In truth, this was not the first time he had come upon a phenomenon like this. Lately, for the last month or so, when he was on a full dive, he would see something shimmering strangely in his field of view sometimes. And never in the normal VR world; it was only when he was accelerated.
But the phenomenon that day was clearer than ever. Haruyuki forgot about his homework and focused his entire mind on what he was seeing.
When he did, he quickly realized something. “A person?”
Right. The shimmering produced at one point in the classroom looked somehow like a human silhouette. It was almost as if a completely transparent human being was standing there.
But there was no way that could be. The blue basic acceleration space was, as a general rule, the world of only the person who had shouted the “burst link” command. In order for two or more people to dive into the same space, in addition to having their Neurolinkers directly connected, they had to execute the acceleration command at the same time. But, of course, Haruyuki was not directing with anyone at the moment.
Which meant: “A—a ghost?” He accidentally murmured the word and scared himself into a gradual retreat toward the back of the classroom.
But the transparent shadow slid toward him by exactly the same amount.
“Eeeeee!!” he shrieked, and dashed backward at top speed. Unconsciously, he started to call out the command to end the acceleration. “B-B-B-B-Burst ou—”
But he stopped there.
This wasn’t the real world; it was a VR space his Neurolinker had generated from images via the social cameras. Everything his eyes were seeing was digital data that could be substituted with code. Thus, there had to be a reason for the presence of that shadow. There were no ghosts. Ghosts were just made-up.
Hiding behind the desks in the last row, Haruyuki racked his brain. There had to be a way to determine exactly what that human form was. Assuming it was another person, this “someone” had to be a Burst Linker like him, because this wasn’t a regular VR space, but an accelerated space. And if there was a Burst Linker connected to the same net…
“R-right. Th-th-there should be a name, then. On the matching list,” he muttered quickly with a dry mouth, and immediately tapped the B icon displayed in the upper left of his virtual desktop. The Brain Burst console screen popped open. He shifted tabs and opened the matching list.
At the very top was his own name. Below that were Takumu (Cyan Pile) and Chiyuri (Lime Bell), both in the same class with him. And then Kuroyukihime (Black Lotus), probably in the lounge. There should have been only these four Burst Linkers at Umesato Junior High.
And yet.
A collection of dots like bleeding ink rose up in the fifth row and squirmed. These points of light didn’t immediately take on the form of letters for some reason. Haruyuki held his breath and watched as they shook fiercely, blinked, and then finally transformed into several letters of the alphabet.
However, the row of letters did not have the standard form of “color, name” that was the template for duel avatar names. A mere six letters were lined up there. There was also no level displayed.
“K-i-r-i…t-o?”
Kirito? Who’s that?
As if guided by this curiosity, Haruyuki’s right hand moved automatically. He tapped the name of this mysterious Burst Linker Kirito and selected DUEL from the pop-up window. He touched YES in the confirmation dialog.
The blue classroom vanished, as if melting away.
While he was passing through the dim space, Haruyuki’s pig avatar was wrapped in light and transformed—into his silver duel avatar with its round helmet and slender limbs, the Burst Linker Silver Crow.
Two green health gauges stretched out on both sides of the upper part of his field of view. In the center, a timer with 1,800 on it was inscribed. And then finally, the flaming text FIGHT! blazed up and exploded.
At the same time as his metallic feet touched the battlefield grounds, Haruyuki lifted his face with a gasp.
Directly in front of him, a little ways off, someone was standing there. Someone that didn’t seem like a duel avatar.
As far as Haruyuki knew, the avatars of all Burst Linkers had hard, robot-like exteriors. There were some players among them in clothing, but by and large, their faces were not those of their real selves.
However, the person standing before him at that moment clearly had taken a human form. It was a boy. Longish hair, and his sharp eyes were jet-black. He was maybe a little older than Haruyuki. He had on a long coat that appeared to be leather, fingerless gloves on his hands, and boots on his feet. And two long items hanging across each other on his back.
“Swords?!” Haruyuki muttered hoarsely, and slowly put some distance between them.
There was no doubt. They were so-called longswords, so familiar in fantasy-type games. The hilts were black and silver. Although they would have been polygons, the way they shone with real weight made him vividly feel the existence of real swords tucked away within those sheaths.
This was not a Brain Burst duel avatar. That said, it didn’t seem like a harmless full-dive avatar, either.
Cautiously scrutinizing his opponent, Haruyuki took a deep breath and shouted, “Who are you?! How on earth did you connect to the Umesato local net?!”
Despite the fact that his voice, tinged with effects, rang out loudly through the field, the black swordsman didn’t so much as twitch. But he wasn’t being ignored. It was more like his voice never reached the other player to begin with.
When he looked very carefully, the outline of the swordsman avatar was hazy like smoke. Haruyuki wondered if he wasn’t real—if only an image was being sent in from somewhere. He took a step forward to check.
In that moment, the swordsman moved as well. The lustrous boots moved a step forward, crunching against the pebbles on the ground of the stage.
This is no virtual image!
Haruyuki hurriedly leapt back again, and his hands snapped into a ready position in front of him.
As if induced by this movement, a tension raced across the face of the swordsman, and in a flash, his right hand was grabbing the black hilt of the sword on his back.
Where exactly am I? And who is that?!
The two questions simply played on repeat in my head.
In the advance lecture, operator Higa had told me that the field I was diving into
was a gentle grassy meadow in the middle of the day. But the scene spreading out around me was the exact opposite of that.
Cracked earth. A half-destroyed blockade of concrete buildings. Tongues of flame licking up out of oil drums. And a night sky without a single star in it. Like the world after the collapse of civilization.
If I had been the only one there, I would have started to wonder if there had been some kind of error with the quantum circuit, and my consciousness had been sent flying to future Tokyo. But fortunately—or perhaps not—a few meters ahead of me was another human form.
The silhouette was human at least. It wore a smooth, round helmet on its head, and the body was completely covered by metallic armor. Compared with the large head, the body, glittering silver as it reflected the light of the bonfires, was extremely slender. To the point where I could hardly believe there was a person inside. And it had something like radiation fins folded up on its back. The front of its helmet was a mirrored visor, and I couldn’t see inside that.
“A robot?” I murmured, and took a step forward to try and find out what it was. The sole of my boot came down on rubble, making a crunching sound.
Instantly, the silver robot flew back quickly and brought both hands up in front of it. It had no weapons. However, the tips of its fingers glinted sharply, making me suspect they held a power that I couldn’t dismiss. The moment this thought occurred to me, my own right hand automatically moved. Over my shoulder to clutch the hilt of a sword slung over my back.
A sword?
Here, I finally realized that I was not Kazuto Kirigaya, real-world high school student, but rather that I had taken on my old familiar form of Kirito the swordsman.
Higa had said that when I dived, my avatar would be automatically generated from my self-image. So that meant that more than my real self, I saw myself as SAO’s Black Swordsman, who no longer existed anywhere. I almost smiled wryly at this, but I was in no situation to lose focus. The mysterious silver robot had readied both hands, and I was holding the hilt of my sword. The situation was basically about to explode.