>>279622853
>Have they had no romantic development this whole time?
I don't think so.

So the premise is you're looking this through the lens of someone (the MC) who uses a rental girlfriend. Are her gestures real or are they just an act? Which feelings are genuine or fake? That's what Kazuya's purpose is to figure out. Everything about her is an illusion. The whole date is a date of "dreams". Kazuya must break out of this delusion of the past month with her. There were never any "feelings" or any "romance", at all. It's all an act with her. As Sayuri (her grandma) said, Chizuru is a true professional actress, always playing a role, always perfectly deceitful.

She has our titular protagonist in an illusory chokehold.