People who don’t think Masa is going to be a romance option, I have bad news:
https://www.multiplechoicestudios.com/samurai-of-hyuga-book-4-released/
Masami is a potential, future RO. Because Masami is depicted as underaged, there will be no intimate scenes with her until after a timeskip in the story. Their relationship with MC can still grow in the meanwhile.