OK!
I just downloaded today's Oha Star, and right after Saki's goodbye VTR, it DOES say a new oha girl is joining tomorrow!
That screenshot I posted above is legit, but I didn't notice before that there's still a sticker on it that's covering some info.
Here's a screenshot I just made that shows what it is.

What it says is "Member of that famous group!!"
The hair length and shape of her sillouette match too!
It's even in her member color!
That seals it! Eripon is the newest member of Oha Girl Maple!