Spoiler! :
If you read sword art online and accel world then you should know that ac is the future of sao, but apparently there are some hints about the characters and things that are in aw have to do with sao.Here is what I think.
First,Underworld is the archtype of Brain Burst.It is because you can accelerate your thoughts 1000 times in both and also 'incarnate system' have a connection with Kirito's thought of 'Using one’s own power to overcome many thousand people’s worth of imagination may sound really frivolous, but in fact, what would happen?' when he was planting flowers that were not suppose to be able to grow the place he is at, in the end he manage to make the flowers bloom.
Second,Haruyuki is Kirito's son!It might be quite shocking but there are some proof. Kirito once said to Asuna in Chapter 9 ''I think the «Brain ImplantChip» research at Santa Clara University is the real successor of the FullDive technology. The Brain Machine Interface is probably heading toward that direction. I really want to see it, where the next world is born.”Now to back aw, in Chapter 3 and 4.Kuroyukihime tried to find the reason why Noumi Seiji is able to avoid being found on the matching list but is still able to challenge other players. He can up with the conclusion 'BIC' but in order to find more information about it. 'He rapidly passed through the endless number of data folders that existed in his Neuro Linker‟s local memory. Eventually, at an absurdly deep level, a folder with only the title [F] appeared. F was the F for „father‟. There, all the information, no, memories that were connected to his real father, who he hadn‟t gotten in touch with once since he left their family long ago, were stored. There were only a few photographs. Voice files. Text memos. And the data folders related to his father‟s work, which he had duplicated from the home server just before his mother completely erased them all.His father had worked as a business manager in a company related to the backbone of the network. Even if his father had hardly come back to the house and had only stayed at home for an occasional rest, the data of his work spread out wide in Haruyuki‟s vision, and he wasn‟t even looking at the other files there besides that. Having remembered that things like the history of VR device development should have been among the documents his father had left in the server, Haruyuki desperately went through the folder while shaking off the prickling feeling piercing his chest. Finally, he found the target file and opened it. He scrolled with his finger through the string of characters that summarized in chronological format. The first headgear-type VR machine that implemented Full Dive technology was marketed in May 2022. The first generation device of the present Neuro Linker was put on the market in April 2031.' After reading the above passage you might think 'So what, His father had worked as a business manager in a company related the backbone of the network. So it surely he will have information about the BIC.' Correct, but I have few more proofs.One, why was his mother deleting those files?Two, can it really be just a coincidence that Kirito was talking about BIC and Haruyuki's father have information(bear in mind that BIC was banned quickly after it was present so i should be hard to have information about BIC) about it?Two last piece of evidence if you have watched accel world ova 2, you will find out that Haruyuki's memories about his father is very hazy. He can't even remember his father's looks(as if his memories were altered)!We also had never seen his mother's face either which make things very suspicious.
Of course it might be my imagination running wild but if you can find more connections please leave it in the comments. Also, my english is not very good so if there some typos please forgive me.
First,Underworld is the archtype of Brain Burst.It is because you can accelerate your thoughts 1000 times in both and also 'incarnate system' have a connection with Kirito's thought of 'Using one’s own power to overcome many thousand people’s worth of imagination may sound really frivolous, but in fact, what would happen?' when he was planting flowers that were not suppose to be able to grow the place he is at, in the end he manage to make the flowers bloom.
Second,Haruyuki is Kirito's son!It might be quite shocking but there are some proof. Kirito once said to Asuna in Chapter 9 ''I think the «Brain ImplantChip» research at Santa Clara University is the real successor of the FullDive technology. The Brain Machine Interface is probably heading toward that direction. I really want to see it, where the next world is born.”Now to back aw, in Chapter 3 and 4.Kuroyukihime tried to find the reason why Noumi Seiji is able to avoid being found on the matching list but is still able to challenge other players. He can up with the conclusion 'BIC' but in order to find more information about it. 'He rapidly passed through the endless number of data folders that existed in his Neuro Linker‟s local memory. Eventually, at an absurdly deep level, a folder with only the title [F] appeared. F was the F for „father‟. There, all the information, no, memories that were connected to his real father, who he hadn‟t gotten in touch with once since he left their family long ago, were stored. There were only a few photographs. Voice files. Text memos. And the data folders related to his father‟s work, which he had duplicated from the home server just before his mother completely erased them all.His father had worked as a business manager in a company related to the backbone of the network. Even if his father had hardly come back to the house and had only stayed at home for an occasional rest, the data of his work spread out wide in Haruyuki‟s vision, and he wasn‟t even looking at the other files there besides that. Having remembered that things like the history of VR device development should have been among the documents his father had left in the server, Haruyuki desperately went through the folder while shaking off the prickling feeling piercing his chest. Finally, he found the target file and opened it. He scrolled with his finger through the string of characters that summarized in chronological format. The first headgear-type VR machine that implemented Full Dive technology was marketed in May 2022. The first generation device of the present Neuro Linker was put on the market in April 2031.' After reading the above passage you might think 'So what, His father had worked as a business manager in a company related the backbone of the network. So it surely he will have information about the BIC.' Correct, but I have few more proofs.One, why was his mother deleting those files?Two, can it really be just a coincidence that Kirito was talking about BIC and Haruyuki's father have information(bear in mind that BIC was banned quickly after it was present so i should be hard to have information about BIC) about it?Two last piece of evidence if you have watched accel world ova 2, you will find out that Haruyuki's memories about his father is very hazy. He can't even remember his father's looks(as if his memories were altered)!We also had never seen his mother's face either which make things very suspicious.
Of course it might be my imagination running wild but if you can find more connections please leave it in the comments. Also, my english is not very good so if there some typos please forgive me.