GamerNode had an interesting interview at E3 with the Tekken Project team in which Harada confirmed that JayCee is in fact Julia Chang. Apparently, she is just filling in for a friend who is in the hospital. Julia puts the mask on and does the lucha libre thing. He further noted that if customize JayCee to remove the mask that the name will show up as Julia Chang. He already has confirmed that it will not change the moveset though, so it will just be the name that changes. So anyone hoping to get Julia’s old moveset/properties back, looks like you’re out of luck.
KH: In the story, Julia has a friend who’s a lucha-libre, very popular with the children and people world-wide. She couldn’t make it to a special wrestling match because she had to go to the hospital, so she asked her good friend Julia to fill in for her. Julia, so no one would know, dons the mask and performs pro wrestling. That’s why the character is changed in that fashion. I haven’t told anyone this ever, but since you’re a Tekken fan I’ll tell you this too: right now her name is JayCee, but the game will feature customization like older games. With this, you can take JayCee’s mask off, and if you do her name will come up as “Julia Chang” instead of JayCee.
JF: I didn’t notice before, but is Julia on the character select screen? If this is how we’ll play as her, will she retain her old moves?
KH: The moveset doesn’t change, it’s mostly Julia already but with quite a few special new moves that are the lucha-libre type. She’s not on the roster, but her name will appear if you take the mask off.