Thread:Sprucetail/@comment-26391060-20140125010009/@comment-6697950-20140125080158

That's volume 7, not 8:

Asuna thought a little about Lisbeth's question. Other than the Undine rapier user «Asuna» which was transferred over from SAO, she also made a new account and trained a new character from scratch: the Sylph «Erika». The reason she created a new character was extremely simple: Sometimes she wanted to change her appearance too.

Erika is definitely a Sylph. The whole point of creating a new account was to have a different looking avatar. Almost all Undine's have blue hair, so making a new Undine won't make you look that much different.