9 is more than enough. In fact, I think Hannah, Misaki, and Akari are slightly too much. I wouldn't mind if they took a back seat and got incorporated later, once MC has more power. They all kind of feel like a 'hey I'm also here' character, that would feel more welcome once the group is fully established.
Rachel's 'punishment' should be running and organizing the harem. After taming her, just use her confident nature to get all the other girls in line, literally and otherwise. Kind of a Yang to MC's Yin, ironically.