It's a combination of her personality, her body language, her voice, and her design.
A lot of people don't really think about it too much, but the reason she comes across as fucking hot is because all of the accessories on her character design add very attractive qualities to the entire design. Look at all the shit she's got on her and see how feminine the design is as a whole.
The ribbon in her hair, the choker, the bracelet, the half fingerless glove she wears, and the asymmetrical socks all add into a surprisingly lewd design. It's attractive, stylish, feminine, and cool all at the same time despite the fact that she can be the biggest fucking dork at times. Now if we combine this all with her now natural voice that she uses instead of that fake ass high pitched shit she was doing before, the way she walks as seen here
>>23607061, and her "Time to win" personality and we have achieved what everyone calls Suisex.