I think O is most likely Keekihime.
The agency being in Osaka (Keeki is obnoxious about having lived in Osaka and speaking with an accent) as well as potentially getting her old spot in that shitty underground idol group makes me believe it's her. Keeki is the only odottemita girl who was in an idol group and she still tries desperately to cling to that fame. I could see her flipping her shit if Himezawa took her spot. The only other person I can think of that was in a group was Kerukkuma but I'm not sure if her group is even still around.
There's also this quote that makes little sense but> There were lots of comments on some passive-aggressive post that I should have a screenshot to avoid all the drama she started, but I was dumb enough not to.
Passive aggressive posts are keeki's bread and butter. I think she's possibly referring to the post Keekihime posted on facebook and lolcow about Venus that Himezawa thought was about her.
The bit about her having girls taking pictures of her at the cafe is so hilarious. Didn't someone on here say that there was another celebrity there or it was a popular cafe in general? This story seems so fucking fake.