I've had several Japanese pen pals, mostly middle aged males and a few house wives. It seems to me that female pen pals are much more demanding and they feel the need to point out more then once they have no sexual interest in you even if nothing was offered to them of this nature in the slightest or even remotely alluded to. In general I had much more to talk about with the guys, they were friendlier and responded more promptly. If you really want your pen pals to be Japanese I suggest you to be flexible regarding gender and age of your pen pals.