We know that Yui was saved in Kirito's NervGear's local memory in the first season of Sword Art Online but in in the second season when Kirito is in Gun Gale Online, when everyone is watching Battle of Bullets Yui is there with everyone else watching it in ALO. she also talks to Asuna on her phone when she heads off to the hospital and in Agil's bar when Kirito sets up the cameras for her.

in all of these cases Kirito isn't using his NervGear and i would suspect it is turned off. so where is Yui now stored? and how is she able to go from this place to ALO, Asuna's Mobile and the cameras in Agil's bar?

  • She is moved to ALO server which is maintained by Asuna's family. Commented Sep 22, 2016 at 6:47
  • @NamikazeSheena i don't think that's correct unless Asuna's Family also owns Ymir. if it's true though would like some citation on that
    – Memor-X
    Commented Sep 22, 2016 at 7:01
  • I believe she gets moved over to Kirito's phone at some point (It's been a while since I read the light novels, so I'm unsure on that), so maybe she's able to join up with Asuna and the rest of the gang through an internet connection?
    – Cyberson
    Commented Sep 22, 2016 at 15:29

4 Answers 4


According to a Q&A session1 (EX00~Face to Face~) in the third popularity contest held by Kawahara Reki, as Kunori Fumio (his webnovel penname), in 2005:

Her core program routine runs and is stored in the local memory of Kirito's NerveGear and takes up about 3TB.

1 Chinese-translated copy of the Q&A session


Ok here's the real answer taken straight from the 5th light novel:

When Aincrad was on the verge of collapsing, her core program was saved to Kazuto’s Nerve Gear and was spared from being deleted. Currently, in Kazuto’s room, she was «living» inside a dedicated stationary-type machine prepared by him.

But, direct contact with Yui was only possible exclusively under a full dive environment - in other words, within ALO only. Although in the real world you could use a mobile phone and have her there, the battery capacity was not long enough and they could not «always be together».

Also, it was meant to be Kirito going into GGO alone without risking anyone else so of course Yui stayed with Asuna.

  • I take it the dedicated stationary-type machine isn't just Kirito's old NerveGear but some other piece of equipment?
    – Memor-X
    Commented Nov 10, 2017 at 0:00

According to Wiki page, she exists in Kirito's NerveGear. Apparently, she connects to game servers and different devices from there through internet connection.


Her program is locater in Kirito's Nervegear hard drive. Kirito during GGO left his helm (probably turned on) in home so she can freely live in ALO. About these devise contacting. She is a program with free access to internet so she can connect herself to devices via internet.

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