Bone handled knife

Just purchased this interesting knife....story with it was that it was Japanese ..WWII....has bone handle, 15 inch blade, appears hand forged, wooden sheath wrapped in woven chords....hilt is mounted with copper band and with a copper/silver Indo Chinese coin dated 1921....well used.....but very nice.....any ideas of origin.....have see this style blade before in other South Pacific relics...,,any ideas would be appreciated ...Randall