In the Princess of the Yen book it was shown that in the post-war Japan BoJ was primarily controlling amount of credit creation (in addition to selecting sector

In the Princess of the Yen book it was shown that in the post-war Japan BoJ was primarily controlling amount of credit creation (in addition to selecting sectors which got it) and that interest rate was a just secondary tool. If a central bank does not have such degree of control over its domestic banks, then it has to use the rate policy, but it's a quite blunt instrument with significantly lagging response (since you can not easily cure systematic risk-aversion, even if loans are dirt cheap). But there is another tool which can be used by colluding with domestic government: debt monetization (a.k.a. "money printing"). It results in the financial system being flushed with newly created base money, thus reducing the need for additional credit. As noted in other comments: many have option to leverage, but prefer not to. Not only because future looks too uncertain, but also because today they have enough cash to get by.