Doyo no Ushi no Hi (土用の丑の日)

▣ What is Doyo no Ushi no Hi, and what makes it so special in Japan?

Doyo no Ushi no Hi, literally ‘the Day of the Ox in the Doyo period,’ is an observance that falls during the peak of the Japanese summer. It’s traditionally the day when eel, especially unagi kabayaki, is eaten to combat summer fatigue and regain energy. This custom is deeply rooted in Japanese popular culture and belief, turning a simple meal into a genuine wellness ritual.

▣ What’s the origin of eating eel on this specific day?

The tradition is said to have roots in the late Edo period, thanks to Hiraga Gennai, a well-known scholar and inventor. Legend has it that an eel restaurant owner, struggling with poor summer business, sought Gennai’s advice. Gennai suggested putting up a sign that read ‘Today is Doyo no Ushi no Hi.’ The idea was a success, and from then on, eating eel on this day became a widespread custom.

▣ How is the date for Doyo no Ushi no Hi calculated, and does it always fall on the same day?

The date isn’t fixed, as it’s tied to the Japanese lunisolar calendar and the cycle of the twelve Chinese zodiac signs. Doyo refers to a period of about 18 days leading up to each seasonal change. The ‘Day of the Ox’ (Ushi no Hi) is the day within that cycle that corresponds to the Ox zodiac sign. It can fall on different dates between late July and early August, sometimes even twice in a single summer.

▣ Why is eel (unagi) considered so energizing for battling the summer heat?

Eel is rich in essential nutrients, including vitamins A, B1, B2, and E, as well as calcium, protein, and healthy fats like DHA and EPA. These properties make it an ideal food to combat the mugginess and exhaustion typical of the Japanese summer. Tradition holds that eating it provides the perfect boost to get through the year’s hottest weather.

▣ How is eel typically prepared and served for Doyo no Ushi no Hi?

The most common way is unagi kabayaki, where the eel is butterflied, deboned, skewered, and grilled, repeatedly brushed with a sweet and savory soy-based sauce (tare). It’s then served hot over a bed of rice, often in a special lacquered box (unaju) or a bowl (unadon). The meat is tender and succulent, with a lightly caramelized crust.

▣ Are there other traditions or alternative foods for those who don’t eat eel on this day?

Absolutely! If eel isn’t your thing, tradition suggests eating any food that starts with the letter ‘U’ (う) in Japanese, such as umeboshi (pickled plums), uri (cucumbers or melons), udon (noodles), or ushikuibetsu (beef; ‘ushi’ means ox). The main idea is still to consume nourishing foods to boost your energy.

▣ How significant is this event in modern Japan, and how is it observed in cities?

Doyo no Ushi no Hi remains a highly cherished and commercially significant event. Supermarkets and convenience stores stock up on ready-to-eat unagi dishes, while specialty restaurants sell out and see long queues. It’s a day that blends tradition with consumerism, with promotions and advertisements everywhere reminding Japanese people to enjoy eel to recharge their energy.

▣ Are there significant regional differences in how Doyo no Ushi no Hi is celebrated?

While the custom of eating eel is widespread throughout Japan, there are slight regional differences in preparation. For example, in the Kanto region (Tokyo), the eel is grilled, then steamed, and finally grilled again with the sauce. In the Kansai region (Osaka), however, the eel is grilled directly without the steaming step, resulting in a crispier texture.

▣ Fun Facts

• The term ‘Doyo’ doesn’t just refer to summer; there are four Doyo periods each year, one before every seasonal change (spring, summer, autumn, and winter). However, the summer Doyo is the most famous, thanks to the eel tradition.

• Despite its strong association with food, Doyo no Ushi no Hi was historically also a time for specific purification rituals or for refreshing oneself with herbal medicinal baths, believed to ward off bad luck and seasonal illnesses.

• The increasing demand for eel on Doyo no Ushi no Hi has raised concerns about the species’ sustainability. Consequently, in recent years, research and efforts to promote sustainable farming and conscious consumption have intensified.