Confirmed!
I won't get too smug about it, but y'all should be happy that I do this. I'm putting valuable time back in the hands of Kayo Aiko fans, so you don't have to spend the hours I've spent finding and presenting little tidbits like this. Remember this picture?
Without a doubt, from left to right: Kago Ai, Ms. Kayo Aiko herself, and Takahashi Ai. Hence, 'aiaiai.jpg'. Also, Tanaka Reina is the person to their right. So my status as an Aiko expert is upheld, ID'ing Reina gets me more points, and the result is not only confirmation that this is a picture of Aiko, but confirmation that she stood between Kago and Takahashi for this picture well after the Morning Musume audition.
The full image (albeit very small) is this:
And the guide to it (with similar family name sounds circled) is this:
How lame is it that the guide is a better resolution than the actual picture? I've never seen any other pictures of this occasion; you'd think they're out there somewhere.
Here is the page where I found it with description in Japanese. I tried my hand at translating it, but could not do it coherently. The most I can decipher is "on one hand, some of them won the audition, on the other hand, some lost. I imagine they had quite a conversation. Do you suppose the order was intentionally based on the sounds in their surnames, or is it coincidence?"
This blogger is one I can identify with. It looks like he (or she) is an avid photographer of places and structures used in H!P photobooks. If I lived in Japan and had the time, I'd do it, too. So let's go get some Nicola pizza and have Blue Seal for dessert.
Also posing with Ms. Kayo Aiko are some Musume greats:
Iida Kaori, Yaguchi Mari, Tsuji Nozomi, Yoshizawa Hitomi, Ishikawa Rika, Kamei Eri, Michishige Sayumi, and Fujimoto Miki, at least. The entire second gen of Tanpopo is there, for those counting.