Why are seashells still common in Japan?

It's simple geography. Japan is a long chain of islands. After you subtract the area of the 5 largest (Shikoku, Kyushu, Honshu, Okinawa and Hokkaido) from the official total nation's area of 378,000 sq km (approx.), you're left with just over 900 square kilometers total across well over 6500 islands. read more

(For comparison purposes, Oahu in Hawaii is about 1,545 sq km; Molokai is about 673 sq km.) Somewhere near 6000 of Japan’s islands are uninhabited- many are simply the tips of underwater volcanic peaks. The ratio of shoreline to island area makes Japan an excellent place for hunting sea shells. read more