Okay, here's the last part.
Everyone wakes up in the student council lounge, and Haruyuki immediately tries to get up - he's eager to go see Rin, since she was basically the reason they did all this in the first place. Fuuko holds him down and removes his cable first, which is a good thing since that would have hurt quite a bit. He and Fuuko leave to go to the infirmary by themselves, and when they get there, the doctor was like "Wow, that was quick." Ha ha ha...
They go over to see Rin, who is sleeping. Fuuko gently wakes her up, and she starts saying she had a dream about everyone and stuff. It seems she's been cured, as the ISS Kits had been deactivated by Red Rider's ghost. The three of them are extremely happy, and Fuuko and Rin embrace each other. Haruyuki gets a hug too, and usually he would stop being able to think completely, but he was too happy for that to happen.
They are going to go back to the student council lounge, but Fuuko says that Kuroyukihime just sent her a message that they're gonna just have a meeting in a normal AW match setting, to tell each other everything that happened.
When they go in, they are in one of the water stages, where the water is only about shin-deep. The school building seems to be floating in it. Crow appears on the roof, but can't find anyone. His cursors are pointing directly in front of him, but nothing is there. Suddenly, Roller comes up behind him and tells him they're directly underneath, inside the building (after trying to use the english "real down" for the word 真下, and being corrected by Crow saying the phrase is probably "right under"). Crow suddenly realizes that he's talking to the bonafide Ash Roller, and is overcome with joy. Their reunion is cut short by Raker telling them that if they don't get down here now she's gonna blow them to bits.
They all go down into the classroom and set up a circle of desks. Crow details everything that happened, up until he got out of the Highest Level. They start talking about AA and CC, wondering why they are gone, and talking about the "true purpose" of Brain Burst. Lotus does note that the message she received upon achieving Level 9 didn't say anything about Level 10 being a game clear condiiton - only that she would get to meet the developer to learn the true purpose behind Brain Burst. So it seems the actual end of the game does indeed lie in the Imperial Castle.
Haruyuki breaks the news that Metatron is gone, but has to bite back his tears once again as a strange female voice comes from outside, on the roof. Everyone rushes outside to see a dummy Duel Avatar of a girl wearing a mask and a white dress. Well, everyone but Black Lotus rushes outside. Black Lotus remains completely still.
She proclaims that she is the White King herself, and that everyone should ask Lotus her Avatar's name later, and begins to talk about AA and CC. Seems she was eavesdropping, but it also seems that she knows way more than all of them anyway. She explains that both worlds died for different reasons - AA for extreme warfare, and CC for extreme peace. Haruyuki guesses that AA was a complete free-for-all type game, and CC was a completely cooperative game. He could understand AA dying for that reason - everyone kills each other and no one is left (and uh in the OVA that came with the games, they actually were the ones that beat the last player remaining, haha) - but not CC. The girl explains that it had stagnated beyond the point of being useful for anything.
Crow has obviously figured out who the girl is by now. Lotus finally steps out and points a sword at her, announcing that she will stand in the way of everything she - and the Acceleration Research Society - is going to do, as she is the president. Haruyuki is astonished at this, but the smarter members of their group (read: pretty much everyone) have figured this out by now, as the building that the ARS's base was in was in Oscillatory Universe's region. Of course, at this point I think only he, Lotus, and Raker know exactly who the White King is. At Rain's challenge, White Cosmos causally says that she would be willing to take Rain on in a battle royale. The battle royale change acceptance screen appears before everyone, and everyone looks to Lotus, who falters in her determination, unsure of what to do.
This is a bit more surprising. A dummy, observer Avatar has even less combat potential than a level 1 Burst Linker. Everyone is a little stunned, especially because that would essentially put her into a one-on-ten battle royale. Haruyuki struggles to grasp the situation. On one hand, it's more than likely she has some sort of secret plan up her sleeve, but on the other, this could be a once-in-a-lifetime chance.
However, right at that moment, he feels what he identifies as Metatron trying to warn him - that twitch in the middle of his back, where the Metatron Wings used to be. It couldn't possibly be her, but it causes Silver Crow to step forward. He shouts at White Cosmos that her invitation isn't fair, since Scarlet Rain doesn't have all her Enhanced Armaments, and demands the last one - the thrusters - be returned to her. White Cosmos refuses, claiming that Wolfram Cerberus/the Calamity Armor is their utmost "hope".
That pisses off Crow, and he starts yelling about all the pain the Calamity Armor has caused in the past. And he's about to start yelling about her treating her sister that way, but Kuroyukihime quietly stops him before that just by saying his name. Crow understands and steps back. Kuroyukihime announces again that they will stand in the way of all her plans, and White Cosmos is delighted that she has finally decided to do so. Then, she turns into a butterfly and disappears into the stormy sky.
Once they get out, they decide to go around and see the rest of the school festival. They get some more food, and bring it up to the roof of the second building to have a picnic. Haruyuki however is depressed - this particular rooftop is exactly where he was always bullied, since the social cameras had a blind spot up here. As everyone proceeds to the lawn chairs set up farther down, Haruyuki stops, in the exact place where if he took another step, he wouldn't be in range of the cameras anymore. He looks down at the slight crack in the floor, unable to overcome the mental barrier it poses.
Kuroyukihime gets his attention. She's standing right next to him, not having taken the step either. She tells him to look to the side. Haruyuki does, and what does he see but a pole with a spherical, black camera attached to it. Speechless, he looks back at Kuroyukihime, who explains that her number one goal of being on the student council was to get this one camera installed right here. There is no longer a single square meter at school that the cameras can't see. Haruyuki still can't believe it, but they take the step over that "line" and proceed to have a picnic.
After they're done with their food, there's yet another emotional scene where Kuroyukihime explains that Red Rider's ghost was the one that disabled the ISS Kit. Yuniko starts talking - a lot - about why she became the Red King, and what it's meant to her, how she feels like she's not really a king right now, even though she leads Prominence. However, Kuroyukihime conveys Red Rider's last words to her - words to the next Red King, that she's done a great job up until now, and he will leave the rest to her. Yuniko can't help but start bawling at this, and starts crying into Pard. Everyone else starts tearing up too. Haruyuki realizes he still has to grieve for Metatron though, but he deflects inquiries as to his suddenly glum facial expression.
After that, it's time for the student council's presentation, and the main event of the culture festival. Megumi comes on over everyone's Neurolinker and starts narrating the whole thing. It's a spectacular presentation. Basically, they use the AR functionality of the Neurolinker to replace every last bit of scenery outside the school building with created video of the ancient past. It starts eight thousand years ago, when where they were was actually underwater, and everything nearby was grassland as far as the eye can see. Hunters and gatherers start to appear and make tiny villages, and Megumi is explaining much of the historical context. They spend a lot of time in the far past, seeing what their area, Suginami, was like over the ages. They start speeding up as they get closer to the present; they see the warring states era, World War II, the rebuilding, and its progression past the reader's present time into the story's present time. As the finale, they progress five years into the future, and into nighttime, to show Helmes Code coming directly over them in the sky. Cargo is shown being transported there, and Megumi explains that in five years, the first human trip to Mars will commence.
After it ends, everyone compliments Kuroyukihime on how amazing that was. Haruyuki's class could only replace the walls with video. She explains that the president is actually really freaking good at this kind of thing, but that she may have used a few points to get some of it done... maybe like 30... and Chiyuri is like THAT'S CHEATING and Kuroyukihime is like shut up I can't think of a better way to use burst points than for something like this lol.
Afterwards, they think about where else they want to go. Pard aggressively pushes the fact that Chiyuri and Kuroyukihime haven't seen his class's presentation yet (though Chiyuri is in the same class, she was busy with track). Haruyuki knows it can't stand up to the student council's grand presentation, but Kuroyukihime wants to go. Also, Fuuko mentions that hte two of them haven't been to the Animal Kingdom Cafe next door, either, while winking at Haruyuki in a way that instantly causes a cold sweat to break out on his back. Was that an order? He had better not say anything otherwise, so he just agrees.
They head for the cafe, and are greeted by whats-her-face oh god I can't remember her name, who is like, oh hey, prez, you here again? heh. Kuroyukihime orders the Nighttime Crow drink and Chiyuri gets the Prankster Cat drink. Everyone goes up to have their pictures taken - normally - and everyone but Kuroyukihime and Chiyuri come back off the stage. Fuuko gets real close to Haruyuki and sweetly says "Okay, you're good to go, Mr. Crow."
Haruyuki: Oh god, was that a direct order? Oh god, it was.
Terrified at what might happen if he refused Fuuko's direct order, he switches the costume setting over the "sexy" version and their clothes start disappearing.
Afterwards, in the hallway, he has a short conversation with Takumu that goes something like,
Takumu: Did you get a picture of that?
Haruyuki: Well... yeah, but they forced me to delete it after.
Takumu: I see...
Takumu: Any chances the data might be recoverable?
Haruyuki: Probably not... but that doesn't mean I won't try.
Takumu: I see. If there's anything I can help you with, please, just say the word.
They're interrupted by Chiyuri asking them what they're whispering about, and they both reply "Nothing" in perfect sync.
As the festival winds down, everyone starts leaving. Yuniko and Pard (what was her real name? I forgot already x_x) leave on Pard's motorcycle, and Fuuko goes to her car to take Rin and Karen/Current/Akira home. Karen thanks them again for freeing her from Seiryuu's "prison", and they leave. Utai says she should be going too; she needs to feed the owl. Haruyuki says he'll help, but she gives him a super-president order to go home and rest. Chiyuri, Takumu, and Kuroyukihime can't go home with him cause they've got stuff to clean up, so Haruyuki goes home by himself.
Of course, his mom isn't getting home until late that night, and Haruyuki starts feeling really lonely. Niko had suggested an afterparty, but everyone's too busy and Haruyuki really needs to rest. While faintly hoping she had snuck in again, or that Chiyuri and Takumu would come sleep over and they'd spend the night playing video games, he flops down on his bed.
He's not tired though, and he keeps thinking about all the stuff he can't do anything about at the moment - the Armor, White Cosmos and her being Kuroyukihime's sister, the Imperial Palace... Everything depends on other people and time at the moment. Finally he remembers about Metatron, and figures he should say good bye properly. He goes into the Unlimited Neutral Field.
It's currently the Ice Stage. Haruyuki wonders if Metatron would have liked it - she probably would, since it's completely white. He starts crying, asking why Metatron had to disappear, even though they had talked about their dreams and going to the end of the Accelerated World. They had only been together for a few hours, but Haruyuki admits to himself that he really liked her. Then he starts getting angry at BB's developer, demanding why he made an enemy like that able to be self-aware and have dreams and thoughts and such, and starts punching the ground (the roof of his apartment building) repeatedly. It starts to hurt, and he wants it to.
He starts getting angry at himself after that. Wasn't there anything he could do? He just floated there and watched as it happens. He keep punching the ground to the point where he might actually destroy his hand, but he didn't care - it's nothing compared to what Metatron went through.
Finally, he calms down a little, and hears an extremely faint voice, as if it's coming from really far away. He can barely make it out. It's not Metatron's voice - it's another voice, who seems to identify itself as something-terasu (amaterasu?), a comrade and friend of Metatron's. As the voice becomes more perceptible, it tells Haruyuki that it isn't too late. Metatron isn't gone just yet - all he has to do is reach out to her.
The voice eventually disappears, and Haruyuki wonders briefly if it was an illusion, but there's no way it could have been. But how would he "reach out" to her? He shuts his eyes and concentrates all his imagination as hard as he can, channeling all the Incarnate possible. He sees a starry sky in his mind's eye, and one start that is extremely faint, but twinkling just a tiny bit. He reaches his hands out to hold it, imagining as hard as he possibly can. He feels his hands finally wrap around the light, and he feels it pulsate.
When he opens his eyes and looks in his hands, though, there's nothing there... until he looks closer and sees a tiny light in them. He feels it pulsate more, and he "thinks harder", and it starts transforming itself back into the icon of Metatron that had followed them around through Tokyo Midtown Tower. Haruyuki is speechless as tears stream from his eyes as her reaches out to touch her.
The moment Metatron fully materializes, she shouts that her slave is foolish and she already told him not to fucking touch him for no reason. Haruyuki can't respond due to being overloaded with emotion, and Metatron, irritated, demands to know why he couldn't figure out that she wasn't completely dead by now - the Metatron Wings didn't disappear along with her, and the danger sense did happen during the confrontation with White Cosmos. She goes on to say that well, yeah he did a decent job with beating the Armor and bringing her back. Unfortunately, she has no real reward to give him.
Finally, Haruyuki can't take it any more, grabs Metatron, hugs her, and curls up into a ball and cries. Metatron doesn't actually have any physical ability to stop him, and the book ends with him crying for a long time.