I only have the vis collections but is there a single story where Akane is
not a principle character.
<<<<<<<<<<<<<<<

Yes. But they are few and are generally one-shot filler stories where
she either doesn't appear (the Herb storyline, where she only appears at
the very beginning and very end and has no or little effect on the plot) or
is only incidental to the plot (such as the cursed ugly bathing suit story). 
All of what I consider to be the good stories, except for the Herb
storyline, feature Akane prominently, however...

tom