> The "ore" (called Tamahagane) is sandy/rocky stone material which needs to be forged repeatedly to remove impurities and get a higher carbon content in the steel.

FWIW tamagahane is already a steel, made from processing ironsand. Tamahagane is not the raw material.

Ironsand is found throughout the world, but outside of the japanese few made actual iron (or steel) out of it historically, because there are usually better sources of iron available.

NZ is an other country which is very poor in iron ore but it has a lot of ironsand, some of its beaches are ironsand (which is genuinely dangerous: it heats up quickly and very high in the sun). While the japanese were largely the only historical users of ironsand, I think NZ is the only one which industrially smelts ironsand.