Don't forget about the harem route either. Anyways from joke apart, personally I think Erika will realize what Sousuke is up to, and she is just a tool in this game between her father and "brother", or maybe Nagi will enlighten her. Or all of this is an even bigger plot, like this whole drama is really about Nagi becoming the new hotel magnate or something like that... I'm rooting for Erika and or Sachi, Ai is a faint ray from the past, but a lot has changed since then, although her feelings seem more real. Hiro and her destiny thing... I think she just toy with him till he finally decide which girl is the one, and she hopes that it will be her...