cell phone question

I am about to go to Japan and live for 5 months and I wanted to know how monthly cellphone charges work. I already have a Japanese cellphone from my last stay, I bought the phone while setting up my mmonthly account, but I had to cancel before returning home. My question is will I be able to set up another account with the same cellphone? Or do I have to buy another cellphone for a new account?
Thanks for the help

Might help to know the phone maker so those with similar models can inform you.
AU?
Docomo?
Softbank?

I have a vodafone. i got it at softbank