Unlike some other japanese guests, didn't see
a single cel where Yuu Watase signed in picture.
I just pointed to around where I wanted sig and
she signed there.  Also, AZ so far doesn't 
force guest to personalize cels (Anime Central
didn't first day but did that Sunday - but
if don't want name on cel rubbing alcohol
on Qtip will take sharpie off acetate).

Also, if don't want to get cel signed can take
blank sheet of acetate w cel and get blank
sheet signed in correct place.

Yuu Watase is pretty friendly, but her eyes
are light sensitive.  If take picture must
not use the flash near her.  Pic below, if shows, 
is her signing my favorite FY cel.