Consumers seeking to beat the summer heat by eating grilled eel, a delicacy famed as a curative for humidity, will also have to swallow higher prices.
July 21 is "Doyo ushi no Hi," a day when grilled eel is traditionally eaten. But this year, the dish will be more expensive than usual across the board, from specialist restaurants to supermarkets and fast-food outlets.
A lackluster eel fry harvest for the second year running is said to be behind the price hike.
Yatsumeya Nishimura, an eel restaurant in Tokyo's Meguro Ward, raised the price of its grilled eel skewer from 1,400 yen ($17.50) to 1,600 yen in July.
A restaurant worker said, "We didn't want to raise the price for July 21, but we were struggling to cover the increase in our supplier's prices."
Eel restaurant chain Tsukiji Miyagawa Honten has an outlet in the Seibu Ikebukuro department store. In May, the outlet raised the price of domestically reared eels by about 10 percent, or 150 yen on average.
The Takashimaya department store in Tokyo also bumped up its prices by 10 percent on last year.
According to industry insiders, eel farms need about 25 tons of eel fry annually to meet demand. However, in both 2010 and 2011, only 20 tons were harvested, causing the price of fry to double and the wholesale price of adult eel to shoot up to 30 percent more than two years ago.
China and Taiwan are also suffering from eel fry shortages. According to a food trading company's official, the price of imported eel from China is now 1.6 times that of last year.
Domestic retailers and restaurants have been hit by the price increases.
While outlets of supermarket operator Daiei Inc. have kept the price of eel the same, they have reduced the portion size.
At convenience stores such as Seven-Eleven and Lawson, eel box lunches are now 100 yen more expensive than last year.
At beef bowl chain restaurant Yoshinoya Co., a regular size eel bowl now costs 550 yen, 50 yen more than last year. A similar restaurant chain, Sukiya, has increased the price of its own eel bowls by 100 yen.
According to the Union of Eel Farmers Corp. of Japan, the amount of eel distributed on the domestic market halved from 156,000 tons in 2001 to 73,000 tons in 2010.
A union official said, "It's possible that the higher prices may lead to a further decline in consumption."