Even the older chapters were closer to this vibe. I miss when he was surviving a school of psychopath delinquents. Now everyone is toned down. Even the MC refusing to pay would never happen.
So, Ooki is an upperclass narcissist who loves being the center of attention and has enjoyed the whole premise of the manga being stared out or being protected. She's making move on the yandere since she's taking away her attention.