maybe sakiko said something along the lines of "what does a goody two shoes like you know about me, stay out of it"
and then chika was like "if i become a delinquent gyaru, will you stop selling yourself"
and so chika started changing her image to draw attention to herself and make people forget the rumors about sakiko
after this, chika and minato will be a bit closer, and minato will stop being so scared of her because after all, chika's attitude is just a show, she's assertive and borderline aggressive, but she's kind and warm
and also, minato will also start seeing her feelings for hibiki in a different light