US and Japan Government Bond Yields

We now know;

1) What an issuer of a reserve currency (US) does when rates hit zero

2) What an issuer of a layer 2 currency (Japan) does when rates hit zero

An issuer of a reserve currency will try to get rates up quickly to tame prices increases, and to create wiggle room for another round of easing.

An issuer of a layer 2 currency has no capacity to raise interest rates because low interest rates was the main driver of the economy.

It will try to keep interest rates low as long as possible, hoping that the issuer of the reserve currency transitions into easing sooner than later.