^
It's unlikely that she'd be back again seeing as how the story arc involving her character is finished. During the last few seasons of Kamen Rider, they've done their story arcs in groupings of 2 episodes per arc. Guest stars during these arcs are usually just hired for their particular arc, unless the character is established as a semi-regular one, the guest actors work is done with the show. As far as I know, Nao's character is not going to be a semi-regular one, so we shouldn't get our hopes up that she'll be back again.
EDIT:
Morning Musume ALL STAR THANKSGIVING SPECIAL (2010.04.03)
~snip~
a few sample caps:
~snip~
Check the lower-left corner of the screencap. It's Yamamoto Yuusuke and Koji Seto (aka Bocchama and Wataru)!