Cheers mate.you need one each
JR owns a chain of convenience stores in stations and sometimes on the outside called "Newdays" you can use the suica as payment there to clear any balance.
Its also worth nothing that if you are paying a lot of cash for things coins really build up. you can use those coins (bar the 1 and 5) to charge your suica
That's also good to know as it's really an unknown to us how much we'll use it so if we do overestimate, I'm sure there's plenty of things we could purchase from Newdays.
I think we will exchange quite a bit of cash beforehand as well so also good to know.