@MickeyMoose
Ooki is the mastermind, but we don't have the whole grasp of whatever she wants to achieve yet, since just now we see the story from her perspective, but still not her thoughts.
She created an elaborate situation in which Katagiri would think her and Okada are on speaking terms (they're not she used him or rather his boobs obsession), which made Katagiri anxious and when she was the most vulnerable she subtly revealed to Katagiri that she knows why she is so ecstatic when she is front of her to get her contact info. She might be after Katagiri, she might be another 'S' playing on Katagiri's feelings, I don't think we know yet.
Okada just lost his mind.
@Lynkaster
Assuming it's his delusion, since I don't think that character is real, he dissed himself.