what if you have a tattoo of your flag

im from australia and going to japan soon i have a tattoo of the southern cross which is on our flag, do you think that would be a problem if its showing while swimming??

The discussions on similar threads like this one:

http://www.japan-guide.com/forum/quereadisplay.html?0+44577

apply to your question. It's not necessarily a question of what or where your tattoo is or what your tattoo means to you. It's that a tattoo, any tattoo, may offend somebody because of a tattoo's meaning in Japanese culture.

But it's not like you have to declare all you tatoos upon entering an onsen or pool. Just be discrete, maybe cover it up if you can, and realize that you may be asked to leave if someone complains or the staff sees it.