All I know is that the photo was taken by Loy Fruel at a Californian convention sometime in the early noughties to June 2008, which is when the book was published. Other than that, I know nothing about the costume or even the photo. In fact, I can't find this photo anywhere online except for where I posted it myself.
Luckily, I've discovered that Loy has an account on this very website under the name kamuishirou1999. I've also found his Twitter, Instagram and Facebook accounts:
https://twitter.com/kamuishirou1999
https://www.instagram.com/fancyloyloy/
https://www.facebook.com/loy.fruel.7
If you can't identify the character, try contacting Loy through these accounts. I must warn you, though, that his Twitter posts are protected and that his Instagram is private. Alternatively, if you or someone else that you know was this exact cosplayer, don't be afraid to tell me.
I'll be over the moon once I finally find the name of this character! I've spent years trying to find the character's identity, to no avail.