Second edit with Movie outfit artworkFukuda Saki has just been confirmed to play by the side of Sho-kun in Yatterman. (and NOT Fukada Kyoko)
You must know her (well, I mainly know her) because she played by the side of Nino in "Haikei Chichiue-sama".
She's been casted for the part of Yatterman 2, Ai-chan. She will be Yatterman 1 (Sho's character) girlfriend.
This has also been confirmed on
Jen's blogThey say the cast for the other characters must be announced during January.

Source:
Chunichi Intertainment*runs away to work (yeah it's 7:10 AM T0T)*
*I'll update with character outfit when I come back XD*
Edit again: I'M SOOOOOOOOOOOOO SORRY I mistook Saki for Kyoko, I saw the google alert only 10 minutes after I woke, posted in a dash and ran to work (from which I only returned now... 12 hours later T0T *dead*), and then I read
aishoni comment on my phone and was "NOOOOOOOOOO I POSTED WRONG INFOS T________________T" *kills self with a Big Mac*
Hum so, this is miss Ai-chan matching outfit:

Picture from NewBokan
Picture from EigaAs for my not-interesting-but-personnal-view, I wasn't impressed by her performance in Haikei... maybe it wa sthe character I didn't like, but I was not impressed. I haven't watched "LIFE" (for fear of being depressed if I ever watch this drama XD), so I don't know any other of her performances. So let's hope she will be good ne.
.... and it really disturb me that she's way to young to play Sho's character girlfriend (well, I have difficulties picturing the two of them).
BUT LET'S WAIT AND SEE!
Again, so sorry for the first wrong information m(_ _)m (makes me want to retreat and live under a rock T0T)
Well the problem for me is that I can't even portray him in the outfit yet xD (I guess the outfit won't be that cartoon-ish though), so I really haven't reach the step of imagining the female characters xDDDD
I thought you wouldn't like that... Sometimes my style is so different from the general arts in common icons.