Sakamoto is more or less a 40 year old wingcommander in a teenage girl's body, who saw miyafuji as a potential recruit. After recruiting her, she more or less sees her as one of the team and that's it. Considering how sakamoto reacted when miyafuji grabbed her breasts, not blushing and embarrassed but simply annoyed, I'm guessing that sakamoto is straight. Miyafuji, on the other hand is apparently a breast obsessed pervert who dreams of having sex with her teammates. Notice how sakamoto wanted a situation report, all military and business like, while miyafuji was busy fondling the unconcious yeager.