♔ Sword Art Online Vol. 7: Mother's Rosario "Since Absolute Sword's so strong, is it possible that... it's someone from SAO?" In response to the whispered question, Lisbeth nodded with a serious expression on her face."I suspected that. But when I asked Kirito what he thought after his fight with Absolute Sword..." "What did Kirito-kun say...?" "He said that there was no way Absolute Sword was originally a SAO player. His reason being..."
"He said that if Absolute Sword existed in that world, «Dual Blades» would've been given to that person instead." -Mother's Rosario ,Chapter 1
♔ Sword Art Online Vol. 9: Alicization Beginning Of course, there was nothing much more to be said about the virtual world. The Nerve Gear and AmuSphere had had a pain absorption function that could remove them almost completely, and the level to which it did so was such that I would wonder if it was too overprotective. Because of this, damage in battles was just a simple increase or decrease in Hit Points. Oh yeah, if such pain existed in Aincrad, I would definitely have been unable to leave the Starting City.
Underworld was a dreamland that was created, and also another reality. -Alicization Beginning Chapter 1