Just a thought and a cautionary note. If the birth year for Kaho is 1991(As stated on Kaho's page in this forum) then she would now be 26 years old. The release date for Yuna Kawase's first video is May 19, 2006, according to IMDB. Her age at the time of her first videos release would have been 15 years old. The reason I mention this is that Yunas videos would be considered "Child Pornography" and the viewing, possession, and/or distribution of Yunas videos would be considered a felony in the U.S.
Like I said, just a thought.
I personally believe Kaho is in her late 20's to early 30's, probably 29 or 30 years old. (I think her birthday is today in fact so wish her a happy birthday on her twitter). The form concerning Kaho/Yuna was the Scanlover forum that proceeded this forum, at least that's where I first saw it. Also, if you know a little Japanese (enough to get into trouble at least) you can find what may be her real name. As a reporter, she published sports articles on the web.