"We had the first and the second sets finished and were watching the third group when this happened," said the official at the cooperative, who declined to be named.
Eating contests are popular events at various regional fairs held in Japan to promote local produce and culture, as in other countries where choking deaths have been reported.
Japan's best known competitive eater is Takeru Kobayashi, who won fame as champion of an annual hot dog eating contest in New York.
After news of the latest death was reported, New York-based Kobayashi tweeted warnings about amateurs trying to eat too much too fast.