If Honoka is really Akiha's half-sister, I am going to stop watching. I hate drama styled plots like this. Imagine......
Honoka : Akiha! Boku wa imoto ga! (
Akiha! I am your sister!)
Akiha : Nyaaaaaaaa!~
It makes a great quote but a lousy storyline. But then again, if Honoka is Sakura's twin separated at birth, I wouldn't mind it at all.