best beachside in Japan

HI!
i am living here for a while and still i coult not find a nice beach side in japan(beside okinawa)
somebody can you suggest me nice beach side in Japan?honestly in kansai aera the seaside is not so nice for swimming...i heard about shirahama in wakayama,is it suitable there for swimking and relax??
i am waiting for your suggestions.

What does "best" mean, exactly?
What do you want to do there? Sunbathe? Snorkel? Surfing?

Have you tried the Satsunan Islands like Amami Oshima? Or Yurigahama in Yoron, Kikugahama in Yamaguchi, or Yuigahama in Kamakura? There are plenty of others.

Heaps in Miyazaki and Kagoshima.

Some west of Fukuoka.

Many long the Kure train line south east of Hiroshima.

I love the beaches of eastern Mexico, Thailand, the Mediterranean, the Aegean, and of course Okinawa, and I can still say that I love the beaches of Setonaikai, as far as Kansai area is concerned. I haven't swam in many of them, but so far I loved southern Awaji Island in Hyogo-ken and southern Nakajima in Ehime-ken. The color is not as pretty because of the type of sea water, but the clarity, the safe and calm waves, the few users, and beautiful litter-free pebble beaches are among my favorites in the world. I've never been to Nanki-Shirahama that you're talking about, but it always looks so beautifully blue from air-craft windows.

As a former resident of Kansai (Osaka and Kyoto), I would say many people will go north to the beaches of Fukui prefecture. I don't say it is the best in Japan, but it is rather convenient and the water is relatively clear. You can easily find "Kaisuiyoku bus" for day trip or an overnight trip.

https://www.sunshinetour.co.jp/natsutabi/wakasa/index.html

It is not seaside beach, but it is scenery and you can swim and good convenience of access from Osaka.

https://www.tripadvisor.jp/Attraction_Review-g298202-d12182795-Reviews...

Shirahama is a beach resort town - my staff were there recently (for a second time) and thought it was pretty good.