The dollar crossed the key 100-yen level for the first time in four years Thursday, on stronger U.S. data but also amid speculation about a report on Japanese capital flows.
The weekly Japanese Ministry of Finance report, due Friday, will show details of the investor activity.
"Everyone keeps waiting for it to show an outflow," said Win Thin, senior currency strategist at Brown Brothers Harriman. "But every week this year, except for three, the Japanese have been net sellers of foreign bonds."
Jobless claims data once more delivered a positive surprise, with 323,000 new claims. That puts the four-week average at 337,000, the lowest level since November 2007.
Traders in markets around the world have been watching for funds to flow out of Japan and into other bond and stock markets since April 4, when the Bank of Japan made an announcement about its easing program. The BOJ made a bold move, doubling its purchase of government bonds. The yen has lost about 15 percent this year.
"People have been testing this level and were not getting anywhere, and it finally broke today," Thin said. "That's been the pattern the last couple of weeks. The U.S. and European markets take the dollar higher, and the Japanese exporters come in and dump dollars and buy yen."
BNP Paribas currency strategist Vassili Serebriakov said the ministry's report is important. Its release was postponed for two weeks because of the Golden Week holiday, so Friday's report will show results for April.
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"We wouldn't expect to see those flows materialize very quickly," Serebriakov said. "Those institutions, like life insurers, are longer-term investors. We wouldn't expect those flows yet," he added.
Serebriakov expects the dollar to continue to rise against the yen, and his year-end target is 105.
—By CNBC's Patti Domm. Follow her on Twitter: @pattidomm.