Tokyo's key Nikkei index closed flat on Wednesday with investors cautious as they eyed results from the race to become the Democratic challenger to US President Donald Trump.
The benchmark Nikkei 225 index inched up 0.08 percent, or 17.33 points, to end at 21,100.06, while the broader Topix index was down 0.17 percent, or 2.62 points, at 1,502.50.
"The Nikkei index rebounded to the 21,200 level at one point, but after that, it moved up and down as the results of the US Democratic race came in," Okasan Online Securities analyst Yoshihiro Ito said in a note.
Joe Biden, a former vice president under Barack Obama, seized the momentum in the race with a string of Super Tuesday victories against leftist rival Bernie Sanders.
The Nikkei had opened lower with investors underwhelmed by the US Federal Reserve's surprise rate cut.
The Fed slashed interest rates in a bid to head off the worst of the economic damage the new coronavirus is wreaking on the world economy.
The dollar fetched 107.41 yen in Asian trade, after briefly dipping below the 107-yen level before Tokyo hours. That compares with 107.16 yen in New York late Tuesday.
In Tokyo, Nintendo advanced 1.22 percent to 37,250 yen while cosmetics giant Shiseido rose 1.45 percent to 6,496 yen.
Banks were lower with Mitsubishi UFJ Financial dropping 2.24 percent to 508.4 yen and Sumitomo Mitsui Financial 2.11 percent to 3,331 yen.
Toyota lost 0.99 percent to 6,974 yen while Honda fell 0.77 percent to 2,741.5 yen