The yen's slide to its weakest level in 39 years looks like a blunt verdict on Japan's policy mix, says Christy Tan at Franklin Templeton Institute. If Japan wants markets to believe in the yen, it must show that monetary normalization isn't optional, and that growth won't depend on permanently cheap money. For that, the Bank of Japan and the government need a more coherent message, says Tan. U.S. rates remain far above Japan's, and markets see the Fed as more likely to stay tight or hike, while interpreting Tokyo's stance as "don't hike too fast, don't choke off growth." Fresh intervention can buy time but it can't repeal arithmetic, says Tan. "As long as investors can borrow cheaply in yen and earn more in dollars, the carry trade will keep carrying the yen away." (fabiana.negrinochoa@wsj.com)