
The Spanish version pretty much confirms Kinosaki’s gender
Okuto: Siste… Oh, no, now you're my "brother" ...right?
It’s even more explicit in the spanish version that usually Okuto refers to Kinosaki as sister and is more used to see her as a woman, English leaned onto that but in Spanish it more on the face.
While it’s not 100% confirmed it’s most likely that Kinosaki was assigned female at birth but is genderfluid.