I checked my Phoenix story and that didn't seem to happen.  Are
you really sure  about this?  I've the Chinese version which is pretty
reliable as I've found out.  Akane  really wasn't even involved in this
story, really.  Shampoo was nowhere to be seem in my  version.
<<<<<<<<<<<<<<<

It happens in the animated storyline, not in the manga.  Unless you have a
Chinese version of the anime, in which case I don't know why it wouldn't
appear...