good beaches in Mainland Japan

hey,

i'm going to visit my girlfriend in Japan this summer and we were planning on taking a break away to a beach for a few days.

We want to be able to go somewhere thats reasonably far away from the Tokyo, Saitama area and also from the Osaka area for various reasons. Also ones which don't have lots and lots of jellyfish (girlfriend really hates the jellyfish)

I know its being rather picky but any help would be greatly appreciated :)

Thanks

Shirahama in Kii Peninsula has a lovely beach but don't know whether there are jellyfish or not. We didn't go into the water, my wife and I just walk bare-footed on the smooth white beach.

Some beaches - http://www.associatedcontent.com/article/818759/backpacking_...

Onjuku(Chiba pref.)and Oarai(Ibaraki pref.) are nice beach a little far from
Tokyo(2hours by train). If you want to go more far beach, how about beach faced "sea of Japan" like Niigata pref?
As for jelly fish, it is said that the they increase after Bon Festival(Aug.15).

Try Shiraishi Island, a relatively unknown but beautiful, clean (no trash!), beach on the Seto Inland Sea in Okayama prefecture. Few jelly fish, this year anyway. They have a website in English; www.moooobar.com

Shirahama beach in Izu peinsula they don't have any jellyfishes in August and September.
I don't know why but I have never seen it there.
http://izu-sakuraya.jp/photograph/beach/shirahamabeach1.htm

Izu penninsula or the tip of Boso penninsula have very scenic, uncrowded beaches. The remote coastline in Wakayama near Osaka has numerous scenic beaches.

Jellyfish aren't entirely avoidable in most places, but usually don't appear until early September.