I don't know. It's possible because the two seem to be together abit after Ami leaves for Ryugyuu Komachi and stuff in the anime, during their first live concert I guess. I mean, it could be a relationship of "role modelness" like Yukiho's case perhaps well, or at least Mami may look up/admire Takane for the princess she is. Yeah, it's a huge age gap, unless one of Takane's lies is that she isn't 18...