For decades Japan has been locked in a deflationary spiral so...

For decades Japan has been locked in a deflationary spiral so interest rates were held at artificially low levels.

In developed economies Central Bank interest rates are typically ahead of inflation to ensure Inflation does not spiral out of control.

Japan has been the opposite for some time with interest rates at 0.5 percent

https://www.statista.com/statistics/1317878/inflation-rate-interest-rate-by-country/

So big players would borrow money in Japan at very low rates and invest in overseas markets at a almost risk free basis. This is known as the Japanese carry trade but with inflation now getting out of control in Japan they will be forced to raise rates and that borrowed money suddenly becomes doubly or 3x more expensive so the borrowers are forced to liquidate stocks to repay the debt.

This produces a waterfall effect as instead of dip buyers you have forced sellers