They didn't. That is a misconception borne out of reading our methods of economic policy onto a different context. The MoF, not the BoJ, controlled not only mon

They didn't. That is a misconception borne out of reading our methods of economic policy onto a different context. The MoF, not the BoJ, controlled not only monetary policy but pretty much all aspects of the economy (they even directed lending by banks at the level of individual loans). This changed in the late 90s but through to the early 90s, it was all the MoF.