KORA BEST GIRL. The FeMC is pretty hot but I personally don't care for sissy content.
FemMC is not sissification. Sissification is turning a traditional male into an effeminate male who likes to get dominated by men and women. When the MC is completely turned into a woman, including genitals and reproductive organs, they are now a woman with a male mindset. In games like this, they are likely to become corrupted while their male mindset fades (with moments like "Oh, god, why can't I stop staring at his bulge!? Why am I so curious how it tastes!?" Stuff like that.) and the caricaturized feminine mindset takes over.
I'm not trying to convince you to enjoy the concept, but they are different in kind.
But yes, Kora is best girl.