The Nikkei Stock Average declined 0.5% to 65907.18 at 0020 GMT, mirroring overnight losses on Wall Street. The downturn reflects growing skepticism about the U.S. Treasury Department's bond buyback plan, which pressured U.S. equities lower on Thursday and is now affecting Japanese markets.

Analysts at In Touch Capital Markets noted that "Markets aren't buying" the plan, highlighting investor doubts about its efficacy. This sentiment spilled over into Tokyo trading, where several major stocks led declines on the benchmark index.

Among the worst performers, Asics dropped 3.5%, Fast Retailing fell 3.4%, and Sumco shed 3.2%. These declines contributed to the broader index weakness.

In currency markets, the dollar traded at 158.98 yen, up from 158.50 yen at Thursday's Tokyo close, indicating continued yen depreciation amid the risk-off mood.