I've noticed that all the various NerveGear iterations in Sword Art Online have three LED's on the left side, labeled POW, WAN, and BLK.

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I think it's safe to say that POW is the power, and WAN is the internet connection. What is BLK?

  • 4
    I haven't found anything official, but a few reddit posts say it might stand for "Brain LinK" since the light appears to only be on when the user is logged in Commented Oct 22, 2018 at 15:19
  • I saw a fanfiction story that claimed something similar, but of course it's not the least bit canon. Also, I don't remember that light ever actually being on-- POW is usually solid green and WAN blinks, but BLK always seemed to be black. Commented Oct 22, 2018 at 15:26
  • 1
    Someone asked the same question on Yahoo! Chiebukuro recently and didn't get answered yet (is that you?). Note that I also failed to find any related info about those LED in Japanese.
    – Aki Tanaka
    Commented Oct 22, 2018 at 15:34
  • @AkiTanaka Not me, just a coincidence (I don't speak Japanese unfortunately). Commented Oct 22, 2018 at 16:04
  • @PlutoThePlanet: BLK is not black, it's slowly blinking blue, see the opening of the Alfheim arc (youtube.com/watch?v=gAi4PwjTfRU) or tinyurl.com/y97m87u8 Commented Nov 9, 2018 at 7:17

2 Answers 2


There is nothing confirmed as of now, however we can see that the most applicable name to give according to online discussions is Brain LinK (BLK)

The blinking may suggest a weak link or solid colored a firm connection and so on.


You see it in season 2, episode 12, 16 minutes in. When Kirito is fighting death gun, Asuna enters his room and the BLK light is blinking blue. Therefore, BLK is the Brain LinK in it's activated mode.

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