Bank of Japan (BoJ) increased the Japan interest rates from 0% (has been that way for decades) to 0.25%. They did this because their currency keeps getting cheaper.

This makes people who borrowed money realized now they have to pay more, no more free money. The money they borrowed was used, among others, into investments; namely Japan Bonds, Japan Stocks. Even the US borrowed from Japan through US Bonds.

Now the people who borrowed started to sell the bonds, the stocks, in order to pay back the loans. This brings the price down.