They say she's a Chinese that comes to Japan right? So it's natural for her to wear her traditional outfit.
Yes. That's what I thought as well
But the female antagonist is wearing a yukata and so are the men in the story. The mc is the only one wearing a Qibao since that her traditional clothing because she is chinese. Yeah that is a manhua but the setting of this arc is in japan. And they also said it at the beginning of chapter 193 that Luxia is a Chinese exchange student.
If this were a manga, the MC usually would have been the one wearing Yukata. But since this is a manhua, she is wearing Qibao.