Originally published on metropolis.co.jp on July 2013

Unagi or Anguilla japonica, aka freshwater eel, comes into its own in midsummer with not one but two Unagi Days (Doyo Ushi no Hi) on July 22 and August 3. The day’s name translates as “late season Ox Day”—harking back to a time when the Chinese Zodiac was often used to delineate the passage of time. A custom of eating foods beginning with “u” on the day has transformed into a modern commercial success as folk bust their way into fine eel restaurants and snap up unagi bento for lunch. But don’t just do it for the tradition. Freshwater eel is also rich in protein, vitamins A, B1, B2, E, calcium, and fatty acids DHA and EPA. It’s also reported to combat summer fatigue, boost stamina and turn your skin shiny and waterproof.