Every summer, as the mercury rises the gourmands of Kansai head for their local eel-cuisine specialist. The custom of eating unagi to alleviate the effects of the summer heat is known as doyō-no-ushi no hi, (day of the ox of the seasonal change period) or doyō-iri (entering the period of seasonal change).

Doyō are the enervating dog days of summer, stretching this year from July 19 to Aug. 8, with the period's sole "Day of the Ox" — a particularly auspicious day to scoff the anguilliform delicacies — falling on Aug. 27.

Theories abound on how the custom originated, most attributing it to an advertising ploy by Gennai Hiraga, an eccentric Edo Period physician, inventor and author of the treatise "On Farting."