@Kraco:

That's not really what I was implying. What you said is all well and good, and mostly if not all true. The problem lies in what kind of position Ranka is now left in. If she was more like Sheryl acted in the beginning of the series, she could easily turn around now and say, "I don't know if I can save everyone, it hurts so much! [she did actually say this much.] Alto-kun, you'll have to show me how you truly feel [blackmailing Alto into leaning towards her.] or I just don't think I have it in me to sing happily!"

We all know that neither Ranka or Sheryl would actually do that in this sort of situation, but that is still the position Ranka is now in.

As for the whole Minmay-Ranka connection, it's mostly how stupidly naive Minmay was, without ever realizing or accepting the consequences of her own actions and how she dealt with the protagonist. Ranka at least carries that same stupid naivette, but she jumps to more conclusions. Sheryl on the other hand, is far more like Misa. Though Sheryl is a bitch and likes to play around with Alto (it is important that she is doing so intentionally rather than naively) when a serious situation arrives, Sheryl is far more mature and doesn't let her emotions get too much in the way.

Lastly, for the coupling, I'll always prefer the tsundere character to the moe character.