ikeda has come up with his own growing method. he makes rows narrower than those used for regular sweet potatoes. planting this way keeps the potatoes from growing too large. most japanese shoppers have little use for small sweet potatoes. but in hong kong, they now fetch about $2 per half kilogram. ikeda's company ships 30 tons of the tubers there every year, including those grown by other farms. sales have tripled over the past three years, and the company has started exporting to singapore and taiwan. ikeda is always looking for ways to increase sales. he sent some workers to hong kong in march with five varieties of sweet potato. their job was to find out which ones people liked. >> translator: they loved stronger tastes. >> translator: they preferred distinctive tastes like really sweet, or spicy. >> reporter: ikeda decided that this year, he'll grow even sweeter potatoes. >> translator: products that don't meet local needs will gradually be forgotten. so we have to keep making improvements. >> reporter: ikeda's story shows t