On Tuesday, you will probably be seeing 土用の丑 (doyō no ushi) on signs at your local supermarket or izakaya. What the hell is this?

Doyō (土用) refers to the 18 days before the change of a season (節分). In the case of 7/21, it refers to the 18 days before the start of autumn or rishhū (立秋), lìqiū in Chinese. This year rishhū is on August 7th.

The beginning of this 18-day period is known as 土用の入り (doyō no iri); the final day, 節分 (setsubun). Yes, there is more than one "setsubun" in Japan—four actually—not just the one in February when people play exorcist and throw beans at demons.

As it is believed that one becomes susceptible to all kinds of ailments when seasons change, the Japanese like to fortify themselves with unagi (grilled eel, pictured), udon, and umeboshi (pickled plums). Why these things? Because they start with "u", just like the "u" in "doyō no Ushi". Yes, that is the reason. Silly, ain' it?

The "do" in "doyō" incidentally means earth/soil, and is one of the five ancient elements, 五行 (Gogyō, or wǔxíng in Chinese). These five elements (fire, water, wood, metal/gold, earth) are also the same as the days in the week. Most people believe these came from China, but they actually came from the Roman Empire, which created the 7-day week and gave us the names for the days which today are still reflected in the Japanese--namely, Nichiyōbi (Sun Day), Getsuyōbi (Moon Day), Kayōbi (Mars/FIre Day), Suiyōbi (Mercury/Water Day), Mokuyōbi (Jupiter/Wood Day), Kinyōbi (Venus/Metal Day) and Doyōbi (Saturn/Earth Day). The order of the days, I believe, was connected to the speed at which they passed through the sky. (I need to double check that.) Interestingly, in Chinese, they just call the days "the first day of the week, the second day of the week", which is kind of what you would expect of a humorless and Godless, Communist dictatorship.

The "ushi" in dōyo no ushi means cow. (As you may know, there are 12 animals in the Chinese zodiac. 12 animals x 5 elements gives us 60 different combinations.)

And so what "dōyo no ushi" actually means is this: "the day of the cow that falls within in the 18 days before the start of a new season according to the ancient luni-solar calendar."

Got that?

But wait! If there are only 12 elements and 18 days of the doyō period, then there must be two doyō no ushi days. Yes, you're right. At least in most years you are. This year, there will be two doyō no ushi. The first (一の丑, ichi no ushi) falls on July 21st; the second (二の丑, ni no ushi), on August 2nd.

Bon appétit!