It's mention in the ALO incident that Yui is stored in Kirito's NerveGear. But its later noted on the AmuSphere page that Kirito eventually used the AmuSphere instead of the NerveGear. Is there any mention of where Yui lives once he switches to the AmuSphere? I suppose she could still be in the NerveGear but it would have to be hooked up for her to interact with ALO.