I know this is really a dumb question but for me...not so much. I can't, for some reason, completely wrap my head around how currency pairs work in the crypto world, or any other world!

Here goes:

I want to trade the BTC/JPN pair. I want to buy BTC and later sell it for JPN. I live in Japan so I want to accumulate as much fiat currency as possible. In order to initial my trade do I also need to have JPN in my account. Currently I only have BTC.

Or will I need to sell my BTC for JPN and then begin trading the BTC/JPN pair?

For some reason...I just can't visualize how this all works.

Can someone explain this to me or point me in the direction that can?