Her metabolism was altered by Happy.  When she absorbs the "fighting 
spirit" She becomes are actual age, or in this case well endowed(sp?) 

The pressure points are used by Ranma to stop Hinako's ability to absorb 
the "fighting spirit".  

Mystic Wolf

On Sat, 20 Apr 1996, Philip Mak wrote:

Can someone clarify this for me... about Ranma's teacher (Hinako), is she 
a kid or an adult? Or does she just change forms when pressure is applied 
on the appropriate pressure points? I've seen a couple of fanfics 
mentioning her but I still can't get this straight.