Donald Trump has repeatedly made waves with emphatic tweets and striking statements, but Japan's former currency chief is more surprised about what the president-elect isn't talking about: the yen.

"What's amazing is that he hasn't said anything about the yen," Tatsuo Yamasaki, a former vice finance minister for international affairs, said in an interview on Thursday. "Last year Yellen was saying that the dollar's effective rate was up 20 percent, and it was holding back exports, weighing on profits, and holding down inflation."

The yen has weakened about 8 percent since Trump's win in November and is down about 26 percent since Prime Minister Shinzo Abe came to power in late December 2012.

Trump has not shied away from bringing up foreign exchange in the past, including promising during the campaign to label China a currency manipulator as soon as he took office. He has also been vocal on trade, vowing to withdraw the U.S. from the Trans-Pacific Partnership negotiations and singling out China, Mexico and Japan at his news conference on Wednesday.

Although Trump did comment on the yen and manipulation in 2015 during the primary, there has been little on the subject from him since, and that has been noticed by those in Japanese policy circles, like Yamasaki.