Moriya Beach, Katsuura

What Seaglassmap found here

One of the cleanest beaches on the Pacific side of Chiba. The white sand is crushed shell, and the little island of Watashima sits 170 m offshore. The glass here is seasonal and it is not on the open sand: collectors report bagfuls in summer and literally none in autumn and winter, so check recent reports before you drive down. Blue and green dominate, white comes clear and frosted, brown is scarce. It sits inside the Minami-Bōsō quasi-national park: glass and pottery are yours, but the shellfish belong to the fishing cooperative. Taking abalone or turban shells here is poaching, with a seven-figure fine.