Japanese charm with 'wave' reverse

Reverse have waves as at Nami ('wave') cash - Japanese coin Kanei Tsuho.

Japanese coinage. Norman Jacobs, Cornelius C.Vermeule III, NY, 1972:

The curious design on the reverse of these coins suggests the waves of the sea which flow and circulate everywhere throughout the world; such was the hoped for case of these coins, at least for the islands of Japan. Beetwen the years 1787 to 1860 over 157 million of these pieces were cast at the rate of four mon.

Image received from Jim Farr.

Those are not words on the obverse. This has to be an amulet or charm which is "redesigned" on a regular japanese cash coin. Such "total picture" amulets are very common in China.