I finished THE iDOLM@STER 2 three more times since my previous post.
My second playthrough was with Yukiho. Unlike Takane, her story is pretty good. She overcomes her fears and becomes more confident. At the end, she sings a self composed song called "First Step".
Since I got her good ending and not the true one, she only sang half of the song and she will finish it when the Producer returns from Hollywood.
Third playthrough with Chihaya. Her story was also good, taking aside the miraculous recovery of her throat injury thanks to the spirit of her deceased little brother that appears in form of a swallow (??).
I managed to get the true ending, that ends with the Producer going to the brother's gravestone, thanking him and asking permission to take Chihaya to Hollywood.
The third playthrough was with Haruka. She screws an audition versus Jupiter team due overwork, but at the end she becomes a great leader. Somewhat boring story...
I did a serious scheduling mistake and was unable to win one of the special festivals, so I got the good ending, when you promises her that you'll return and become her Producer again.
I got an A rank with Yukiho and S rank with Haruka and Chihaya.