TOKYO (BLOOMBERG) - While global investors have dumped the Japanese yen in recent months, Mr Gabriel Leung, who runs a small money exchange shop in Hong Kong, has noticed a surge in customers doing the exact opposite.

Amateur investors have been swapping their bills for yen at Leung's Birdy Exchange in the city's crowded, working-class neighbourhood of Sham Shui Po, seeing a buying opportunity after the currency's fall to its weakest levels against the Hong Kong dollar in two decades.

Around 300 customers each day buy the yen, compared with less than a dozen such orders before the global sell-off began, he said.

"Each customer is buying between HK$100,000 and HK$500,000 (between S$17,640 and S$88,200) worth of yen, compared with less than HK$20,000 previously," said Mr Leung, adding that many of the yen buyers plan to visit Japan when the country begins accepting more tourists.

Japan has recently begun relaxing its border controls, but tourists are still restricted to a small number of chaperoned tours.

A divergence in interest rates, with markets expecting the Bank of Japan to maintain rock-bottom rates on Friday despite a hike by the United States Federal Reserve, has driven the yen lower.

But the prospective travellers appeared be focused on the opportunity for deeply discounted shopping rather than the risk of missing out on better rates later.

Mr Philip Ma, a 33-year-old who runs a business selling goods imported from Japan, bought HK$300,000 worth of yen in May and plans to buy more if the currency weakens further.

"I have been buying yen for so many years, and this is the first time it has plunged so low," he said, adding that many of his friends are also buying the yen. "They all want to travel to Japan at some point."

Traders in Taiwan say retail investors there are making similar bets, with the volume of Taiwan dollar-to-yen transactions in June already exceeding that of April. The traders asked not to be named as they were not authorised to comment publicly.