I don't recognize her either- it might be one of the announcer/MC girls from the final tournament in the Three Kings Saga.
It could also be one of the contestants/one of Raizen's old friends who competed in the tournament, the guy that won had a blonde wife, but if I recall she had short, foofy hair.
My best guess would have to be a fan character belonging to the artist who drew this though; no one in the series looks like that.
