Just.. perfect xD. First Mitsuru, and now Naga, you´re like my cosplay idol xD. Loved the background too. Congrats.
Your costume is excellent, but just as importantly, you do very much resemble Naga! I've been a Slayers fan for something like 10 years and I'm fairly picky about who works for me as my favorite characters. But I think you did a wonderful job!
What makes me really truly fangirl over your Naga is that you look so much like her--not just your physique but your facial features. It is so awesome; great choice of a costume! Hurray for Slayers fandom!