So, in episode 22 of Sword Art Online II...

We learn that Konno Yuuki has incurable super-AIDS, and that she's terminal. That's no fun.

But we know that there's technology out there that can digitize your brain - that's exactly what Kayaba Akihiko did, and nowadays he goes around haunting VRMMOs (or something).

Why can't they do the same for her and other people faced with the same issue? It's not a great solution, granted, but she's already used to spending oodles of time in full-dive, and I imagine it's preferable to death.

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    I imagine that it's not a simple procedure. Kayaba was a genius, I don't think anyone can just do it, and since he disappeared, no one can ask him how he did it. Commented Dec 7, 2014 at 11:14
  • i was under the impression the chance that uploading himself had a one in ten chance of actually working or something like that
    – IG_42
    Commented Dec 7, 2014 at 17:37
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    I haven't seen past Sword Art Online 1 but unless it's stated otherwise it's not confirmed that Kayaba was even successful. he tried but most have assumed that he fried his brain in the process killing him and the one that appeared to Kirito in ALO calls himself an echo of the real him (impressive echo though).
    – Memor-X
    Commented Dec 7, 2014 at 21:57
  • in my opinion if i had the same condition, at the terminal point of my life where the condition causes too much suffering i would risk it since i am now on death's door, rather than wait for the condition to slowly open the doors for me i will risk everything and do the same Kayaba, if i fail at least i smashed open those doors and give Death some extra work to do
    – Memor-X
    Commented Dec 7, 2014 at 21:59

2 Answers 2


That answer will contain spoilers from Alicization arc, which has not been animated yet.

Firstly, what Kayaba Akihiko uploaded onto The Seed wasn't his brain, not exactly — it was a copy of his "soul". As explained in the light novel: We have copied the Fluctlight of a number of test subject, and the Fluctlight is what passes through our neurons, so it's basically our soul. However, even though the process of copying somebody's soul is not risky for the real person, it is the case for the copies, because they will just "think" they were the real one and not just a copy. Most of the copies will simply cease to exist as they realize they aren't the original. Kayaba Akihiko's case was an exception, because his real self had already prepared to leave the real world to live in his own creation. So that's the major problem. Once Konno Yuuki realizes that she isn't real but just a copy, she would cease to exist.

The second problem is that the machine to perform the operation isn't public nor medical, and no one (except Kirito and a few others) knows of its existence, let alone where and how to do it.

In the Alicization arc of the light novels (especially the first two volumes of the arc), the details are much better explained than what I have here (they actually exaggerate with the explanation of pseudo-science, but well...), so I would recommend you to pick them up if you are into reading, as the Alicization arc is the best up to now in my opinion.


They don't do it because of the fail rate. The scan according to the light novels has an extremely small rate of success, and the scan almost certainly fries the brain.

Quoted from Sword Art Online Volume 4 - Fairy Dance, Chapter 9 (translation courtesy of Baka-Tsuki):

It seemed Kayaba had decided to die with the collapse of the world of SAO before the incident even occurred. But it was an unusual way to die. It seems he remodeled a FullDive machine to perform a super-high-power scan of his brain, where it burned out his brain and killed him.

The probability of the scan being successful wasn’t even 1 in 1000 - and, although it was baseless, she told me that in her heart she had the feeling that he somehow had succeeded.

If it worked as Kayaba intended, his own memories and thoughts, all of the electrical signals in his brain should have became digital code and should exist in the network as a real electronic brain.

It is safe to assume that it's for the above reason they don't do it.

  • Do you have a book/page reference, or a quote from the light novels to support this?
    – Cattua
    Commented Dec 11, 2014 at 0:25
  • Unfortunately not, was reading the fan translation back before it was taken down from Baka Tsuki due to it getting licensed in NA. I'll look for one and update, in the meantime I edited my answer to better explain what was in the book.
    – Saphiric
    Commented Dec 11, 2014 at 0:33
  • I have added the relevant quote to support what you said. However, I also removed the part about "not confirmed whether Kayaba succeeded or not", since Kayaba did succeeded in appearing near the end of Fairy Dance to help Kirito, and Kirito's reflection right after the quoted part above also kind of implies that Kayaba really succeeded. If you have a different opinion, feel free to copy it from the revision and restore it, but please back it up with your reasoning
    – nhahtdh
    Commented Dec 11, 2014 at 13:40
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    @キルア It's on pages 277-8 of book 4 in Japanese: 「茅場は、SAO世界の崩壊とともに命を絶つことを、事件を起こす以前から決意していたらしい。しかしその死に方が異常だった。彼は、フルダイブシステムを改造したマシンで己の大脳に超高出力のスキャニングを行い、脳を焼き切って死んだそうだ。   スキャンが成功する確率は千分の一もありませんでしたが――、と、どこか儚げであり同時に芯の強さも感じさせる女性は言った。   もし茅場の意図したとおりの結果となれば、彼は己の記憶と思考、つまり大脳内部の電気反応を全てデジタルコードに置き換え、本当の意味での電脳となってネットワーク内に存在するはずだ、と」 (I put in spaces where there are paragraph breaks in the original.)
    – user225
    Commented Jan 21, 2015 at 20:35

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