It had already been five years since the largest network in the world, known as the global net, had transcended the global-ness of its name. The net had been connected to the space elevator station, which was in geostationary orbit above the eastern Pacific Ocean, and also to the international, multipurpose lunar base, such that anyone—if they were so inclined—could dive from their own home into a real-time image of the surface of the moon.

Naturally, countless other nets existed: large-scale closed nets, protected by national and corporate firewalls; local nets in schools and apartment complexes; private nets run by individuals. The assorted systems were multilayered, and if, hypothetically, the signals flying back and forth within them were to be made visible, a dense blanket of intricate stitching, palely glittering, would veil the world.

Although it was quite modest in comparison, the net of most critical significance to Haruyuki Arita was about to appear, at that very moment, in his own bedroom.

“O-okay, I’m connecting, Chiyu,” he announced in a slightly shrill voice, and Chiyu—that is to say, Chiyuri Kurashima—replied, without a hint of nervousness crossing her face.

“What’re you making such a big deal for? Just do it already.”

Howling in his heart that she didn’t understand how he felt, Haruyuki took the plug in his left hand and inserted it into the Neurolinker on his neck. Two “wired connection” notices blinked to red life in the center of his vision, then disappeared.

Chiyu, sitting on the bed, had XSB cables stretched out from the two connectors on her violet Neurolinker. One reached out to Haruyuki, who was plopped down on the floor, and the other linked her to Taku’s neck—that is to say, Takumu Mayuzumi’s—as he sat in a mesh office chair.

Haruyuki shouldn’t have been so nervous about making this connection. In fact, the real issue was—

“Y-you don’t actually need me to direct link with you guys—” he stammered, and Chiyuri favored him with a long stare from her catlike eyes.

“Noooo way. You promised you’d install it for me if Taku’s copy doesn’t work. I’m not letting you get away.”

“…Fine.” He nodded and glanced to his right, where Takumu offered a brief wry smile while pushing up his frameless glasses.

Haruyuki, Chiyuri, and Takumu had been born the same year in a large condo complex in South Koenji and had basically been friends ever since. Going through essentially everything together, they used to hang out every day, occasionally fighting for no reason, then making up for the same. But three years earlier, when they were eleven, Chiyuri and Takumu had started dating, and Haruyuki had pulled back. As a result, the former equilateral triangle of their relationship had stretched into an isosceles, with one corner receding into the distance.

However, with a certain incident the previous year as the catalyst, their relationship had been completely reset, and things had been, in truth, somewhat delicate for the past six months.

Haruyuki simply wanted Chiyuri and Takumu to hurry and make up already. But because Takumu, the cause of the incident, continued to blame himself, he couldn’t bring himself to actively reach out to her. Thus the triangle was unstable, stretching and squashing with each new day…exactly like the two cables swinging erratically between the three Neurolinkers at that very moment.

“All right. You ready, Chi?”

Takumu spoke softly, with a tone that gave no hint as to his inner thoughts.

Chiyuri bobbed her head, sending short hair swinging. She clenched both hands on her small knees, which peeked out from under the hem of her skirt.

Takumu returned her nod and flicked a long finger in the air, running it along the virtual desktop only he could see. But once he had grabbed the file, his pale digit lingered in midair, stopped by a slight hesitation.

“Chi. I’m about to send you Brain Burst, but I just want to check one last time. It’s a game and it’s also not a game. You’ll get the most amazing privileges, the total rush of it, and some serious thrills, but it will demand a lot from you in exchange. You…might regret this someday.”

Takumu was giving voice to the very misgivings in Haruyuki’s own heart.

Once you installed the mysterious game application known as Brain Burst and became a Burst Linker, you gained the ability to “accelerate,” and you could never go back. You were caught up in the previously unknown net of the accelerated world, and you had to duel endlessly, for all eternity, to protect the privilege of connecting to that world. The pressure of this could warp personalities; Takumu had set up a backdoor virus in Chiyuri’s Neurolinker and temporarily broken off their friendship because he had been backed into a corner by his fear of losing the power of acceleration.

Faced with furrowed foreheads on either side, Chiyuri puffed up her cheeks and sharply announced, “Look! The reason I said I want to be a Burst whatchamacallit isn’t because I want this accelerating power thingy. And I definitely don’t want to be that girl’s servant! But this whole super-serious thing you two’ve got going is seriously bugging the hell out of me! Which is why I’m totally going to show you that you need to have more fun with this game!”

Jerking their heads back involuntarily, Haruyuki and Takumu exchanged a look and smiled, strained.

“G-got it, I got it, Chi. Okay. Ready? I’m sending it.”

“Go right ahead.” Chiyuri jerked her sharp chin upward, urging him on with a wink.

Takumu turned toward her and slid his fingertip through the air and Chiyuri’s large eyes became focused on a single point in space. The dialogue to confirm the installation of the application BRAIN BURST 2039 should have opened in front of her. Bringing her right hand up from her lap, she thrust her index finger at the position of the YES button without any sign of hesitation.

“Ah?!” Her small, pink-sweatered body bounced up on the edge of the bed, wide-open eyes rolling from side to side.

Haruyuki recalled the time six months earlier when he himself had received the Brain Burst app. The instant he clicked the YES button, virtual flames had erupted to fill his vision, flames that were displayed to check the acceleration aptitude of the program’s installer.

To become a Burst Linker, you needed to clear two bars. The first was having been equipped with a Neurolinker since immediately after birth, and Chiyuri cleared that one with flying colors. The problem, however, was with the second bar: brain reaction speed.

A Neurolinker communicated with the brain of its wearer through wireless quantum signals. But the brain was an organ inside a living body, and its responsiveness differed with the individual. You might have been born with highly reactive nerve circuits or you might be able to improve your reaction speed through long-term training, but either way, if the speed of your brain’s responses to your Neurolinker did not exceed a certain threshold, the phantom flames would die out halfway through, and your attempted installation of Brain Burst would fail.

But maybe it would be better if it did fail, Haruyuki thought abruptly, sweaty hands clenched tight. The accelerated world was a swirling morass of the raw emotions of the people who fought there—hatred and resentment, jealousy and desire, and all kinds of other ill will. He definitely did not want to see their cherubically innocent Chiyuri hurt by her exposure to that swamp.

“Haru.” Takumu’s voice reverberated suddenly inside his head, a voice that only Haruyuki heard. He glanced over and saw his childhood friend on the chair, lightly biting his lip. “I…I’m scared. Of Chi…changing.”

Haruyuki flicked at his virtual desktop to similarly direct his voice only at Takumu. He replied, “If we—No, if you protect her, I’m sure she’ll be fine, Taku. And it’s not for sure that the installation will work. I mean, I feel bad for Chiyu, but it probably won’t.”

“R-right. She said she was doing some kind of amazing special training or something, but I can’t believe anyone could develop the aptitude in just a couple months—”

At that moment, Chiyuri’s eyes abruptly stopped whirling around to take in the various visions, and then came to fix her gaze straight ahead. She pulled her rather thick eyebrows together, and her focus traveled from left to right. Her lips parted slightly, and a real-world murmur slipped out from between them; Haruyuki and Takumu listened with bated breath.

“What is this? W-welcome to the…accelerated world?”