And thus, the day's extra lessons ended.
It was 6:40 PM. Kamijou had missed the last train that left at the time all students were supposed to have left school, so he was leisurely walking through a shopping district. In order to prevent students from spending all night out, the last trains and buses in Academy City all left at 6:30 PM. The idea was that people would not go out late at night if the transportation system was stopped.
(I'm not sure if I should be glad it's only one more day or be complaining that there's still another day. At any rate, this has gone on way too long. Dammit. Once it's all over, I'm going to the beach!)
Kamijou thought to himself as he returned home that evening. It didn't look like the wind was blowing, but the blades of the wind turbines were definitely turning.
"Mh?"
Kamijou spotted a familiar-looking back amid the crowd. It belonged to a brown-haired girl wearing a Tokiwadai Middle School summer uniform. It was Misaka Mikoto.
Kamijou had no real reason to avoid her, so he jogged a bit to catch up with her.
"Hey. Are you on the way home from some extra lessons, too?"
"Ahn?" was Mikoto's unfeminine response. "Oh, it's you. I'm pretty tired and I want to preserve the strength I have left, so don't make me biri biri you. So what do you want?"
"Nothing really. We just happened to be on the same road, so I just thought we could walk together."
"Oh?" Mikoto's eyes narrowed a bit. "You 'just thought' you could walk with a Tokiwadai lady? Heh. Do you have any idea how much effort guys put into taking that position?"
"…It's pretty bad to be referring to yourself as a 'Tokiwadai lady'."
"I was joking, you idiot." Mikoto stuck her tongue out a bit. "What you learn at your school is more important than where you go to school, anyway. I'm sure you're old enough to know at least that much."
"Hmm. Well, everyone has their own field they specialize in. By the way, is your little sister not with you? I wanted to thank her for carrying the drinks yesterday."
Mikoto's eyebrows twitched slightly.
It was only a few millimeters, but those few millimeters seemed odd to Kamijou.
"My little sister…? Did you meet her after that?"
"Yeah…"
(Crap.)
Kamijou recalled that Mikoto had grabbed Misaka Imouto's hand and forcibly pulled her away from him. Should he have kept it a secret that they met after that?
Mikoto narrowed her eyes slightly.
"Are you that interested in this little sister?"
"No. I just wanted to thank her for carrying the drinks yester-…"
"So you choose the little sister despite us being visually identical? Or can you not choose and you want both of us together?"
"I said no! Where the hell did you get that kind of knowledge!!"
Kamijou and Mikoto walked along a main street continuing their argument in that vein.
Many different wind turbines stood along the street. Kamijou looked up at the spinning blades and then noticed a blimp floating in the evening sky. The exhibition screen on the side was displaying the day's news. Apparently, three research facilities related to muscular dystrophy had been evacuated over a two week period and there was concern over the intense cold coming to the entire city.
The conversation trailed off because Kamijou's focus turned to the blimp. A blimp may sound old-fashioned, but it used solar power to heat carbon dioxide with a heater for lift and to spin a large motor for thrust, so it was an ecological craft that did not need fuel.
Because of the effort that must have gone into developing the thing, Kamijou wondered if the world's supply of oil was about to run out. The concept didn't particularly bother him.
"I hate those blimps," Mikoto muttered.
"Ahn? Why?" Kamijou asked as he looked back up toward the blimp. He was pretty sure he had heard that the blimps had been sent out because Academy City's board of directors had said the students needed to be more aware of current events.
"…Because people follow the policies decided on by a machine," said Mikoto quietly in response as if she were spitting out something that annoyed her greatly.
Kamijou turned his gaze back to Mikoto in surprise. There was nothing odd about her face. There was nothing odd at all. It was as if a crumbling clay mask had been remade while he wasn't looking.
"What's with you? What's that thing called? Um…Tree Diagram, was it? Hah, are you the kind of person that can't stand it when a machine beats a human at chess?"
Simply put, Tree Diagram was the world's smartest super computer. It was the ultimate simulator created under the pretext of being a perfect weather forecaster.
Weather forecasting may sound familiar, but that was a field where things could only be forecasted. They could not be declared as fact. Because the movements of each of the air particles that created "weather" were incredibly complex and intertwined with the butterfly effect and chaos theory, one could say that there was an 80% chance of rain the next day, but one could not say that it would definitely rain at 9:10:00 AM. That started to enter into the realm of quantum mechanics.
However, Tree Diagram had moved weather forecasting to weather predicting.
It did not do anything complicated. Basically, if it could perfectly predict the movements of every particle in the air around the world, there was only one answer it could come up with.
Tree Diagram had ridiculous enough specs to do that, but some people theorized that its use for weather forecasting was just a front and it actually had some other true use.
Incidentally, there was one irregular aspect of Tree Diagram's weather forecasts.
It calculated the weather forecast for an entire month all at once.
There was no real problem with that because it was still accurate, but it still seemed like unnecessary effort. After all, next month's weather was much, much more likely to be off than tomorrow's weather. If the goal was accurate weather forecasts, it would be better to redo the calculations each day.
Yet the Tree Diagram used the more difficult method.
It was rumored that the leftover time was used for research simulations.
Drug reactions, physiological reactions, electrical reactions, and all sorts of other things could be calculated by Tree Diagram and a couple of tests could confirm the answer given. Being able to create a new drug like that almost sounded crazy. According to the rumor, there were researchers that did not know how to use a test tube and who did not like touching lab rats.
A super computer with that much power had plenty of enemies. Human supremacists who hated machines could try to blow it up in a terrorist attack at any time and AI supremacists who hated people might try to sneak into the storage area for Tree Diagram to steal the technology.
In order to protect it from external enemies, Tree Diagram was currently kept in a place where human hands could not reach it.
Basically, the satellite launched by Academy City was Tree Diagram.
The fact that Academy City could privately use the kind of rocket technology that was usually only allowed by national agencies showed just how much influence Academy City had on the world.
(Well, the fact they allowed it also shows how valuable it was.)
Kamijou stared blankly up at the evening sky. Tree Diagram was orbiting outside the atmosphere even then and it was possible it would continue calculating even if the world ended.
"It's a steel brain watching down on mankind from above, but it can't turn on us or anything. This isn't some cheap SF movie. It's just like a bank ATM. It operates according to the buttons you press."
No matter how powerful a supercomputer it was, Tree Diagram could only operate based on the commands people gave it. It was the same as how ATMs did not ruin people's lives because machines were revolting. They did it because they were not being used properly.
"…"
Mikoto did not respond and looked up into the evening sky again. Kamijou couldn't tell if she was looking at the blimp or if her gaze went even further into the distance than that.
"Tree Diagram…The world's most powerful super computer that was launched aboard Academy City's satellite, Orihime I, in order to analyze weather data. It has been determined that no one else will catch up to its level in another 25 years," Mikoto muttered almost under her breath as if she were reading from an Academy City pamphlet. "They say that, but does such a ridiculous absolute simulator really exist?"
"Hah?"
Kamijou looked back toward Mikoto's face, but…
"Just kidding! Ah, I think I started to become a poet or something. Ah ha ha ha ha!!"
Mikoto suddenly chopped Kamijou for no reason.
Standing before him was indeed the lively, smart-assed, and selfish Misaka Mikoto.
"Ow! What the hell was that for!?"
"You really don't have any dreams, do you? Doesn't a friendship drama between a human and a high-level SF computer with a human heart sound like it would have some romance to it!?"
"Listen, dammit…"
"Or what about a maid battle robot?"
"I said listen! And there's no romance or any kind of friendship drama-like stuff to that thing! And are you really a 'lady'!? I thought a lady read romance novels with a cup of tea in hand!?"
"Hahn? Stop that, please. What age is that idol of an image from? I'm human too, so I read manga at the convenience store every Monday and Wednesday."
"Buy it! That's just being a nuisance!"
"Well, I have to go this way," Mikoto said ignoring Kamijou's yell.
Mikoto's spirits had been changing from instant to instant, but she then left. Kamijou blankly watched her leave with a puzzled look on his face.
"…I don't understand her. Is this what you call the characteristics of puberty? Or does she just hate me?"