eel coffee mug

There are various theories about the origin of the custom of eating eel (according to Gennai HIRAGA), and the best known theory is that it was invented by Gennai HIRAGA (1728 - 1780) from Sanuki Province. According to the report, an eel restaurant that was not successful in business went to Gennai to ask him to sell eel that could not be sold in summer. Gennai wrote that "Today is the day of the ox" and advised to stick it to the store front. The eel restaurant became very prosperous. After that, other eel restaurants began to imitate this custom, and it is said that the custom of eating eel became established on the day of the ox in the Doyo. There are various theories as to why the pasted paper on which the letter 'Ushi no hi' was written was effective, but one theory says that 'If you eat something with the letter 'u' on the Ox day, you will not lose in summer.' wikipedia Citation