The Internet company has hired advisers to help it evaluate options for the stake, Chief Executive Officer Marissa Mayer told investors on a conference call on Tuesday. It will not be included in the planned spin-off of its stake in China's Alibaba Group Holding, she said.
Investors have been urging Mayer to monetize the Yahoo Japan stake separately, after she announced plans to spin off the Alibaba stake in January, which could be worth $40 billion.
The advisers will help Yahoo "determine the most promising opportunities to maximize value" for the Yahoo Japan stake, said Mayer.
Yahoo shares rose after the announcement, following disappointing earnings results, trading up about 1 percent from their close at $44.49 on Nasdaq.
But Wall Street remained broadly cautious about the plan.
"They are taking the slow train, stressing the process," said Colin Gillis, an analyst BGC Partners, who warned that a deal, if any, could be a long way down the line. "Engaging advisers doesn't mean spinning it out."
Yahoo owns about 35 percent of Yahoo Japan, which has a market value of almost $25 billion on the Tokyo Stock Exchange. Japanese internet company SoftBank is the biggest shareholder, with about 36 percent, according to Thomson Reuters data.
Last month Yahoo shareholder Starboard Value LP said the Alibaba spin-off was a "good first step" but urged Yahoo to also spin off its Yahoo Japan stake in a tax-efficient manner. Starboard did not reply to a request for comment on Tuesday.