b) If you were the head of the Japanese Central Bank, how would you respond if your goal was to keep the interest rates at the original equilibrium level (before the increase in the taxes) in the money market?

If the goal is to keep the interest rates at the original equilibrium level in the money market, as the head of the Japanese Central Bank, there are a few possible responses that can be considered:

1. Open Market Operations: The Central Bank can engage in open market operations by buying government bonds from commercial banks. This will increase the money supply in the market, leading to a decrease in interest rates. By doing so, the Central Bank can counteract any potential increase in interest rates due to the tax increase.

To execute this strategy, the Central Bank will need to use the tools at its disposal, such as the Bank's reserve requirement and its ability to create money. By actively purchasing government bonds from commercial banks, the Central Bank can inject liquidity into the market and thereby increase the money supply, ensuring that interest rates do not rise.

2. Communication and Forward Guidance: Another method is through communication and forward guidance. The Central Bank can inform the public, investors, and market participants about its intention to maintain interest rates at the original equilibrium level. By providing transparency and clarity on its monetary policy stance, the Central Bank can influence market expectations and shape borrowing and lending decisions accordingly.

By providing clear guidance, the Central Bank can influence market participants to keep interest rates aligned with the original equilibrium level, avoiding any unintended increase resulting from the tax increase.

3. Adjusting Reserve Requirement: The Central Bank can also adjust the reserve requirement for commercial banks. By decreasing the reserve requirement, banks will have more funds available for lending, increasing the money supply in the market. This increased liquidity can help offset any potential upward pressure on interest rates caused by the tax increase.

It is important to note that these strategies may have limitations and their effectiveness can vary based on various factors, such as the level of economic activity, market conditions, and the response of market participants. The Central Bank may need to monitor the situation closely and be prepared to adjust its strategies accordingly to achieve its goal of maintaining interest rates at the original equilibrium level.