Doyo no Ushi no Hi: Why Japan Eats Eel in Summer
Why do Japanese people eat eel in summer?
Every July, Japan celebrates Doyō no Ushi no Hi, the Midsummer Day of the Ox, with one delicious dish: unagi, or grilled freshwater eel. This beloved tradition blends centuries-old folk customs with a modern love for seasonal food. In this article, we’ll explore the story behind the holiday, the health benefits of unagi, and how you can enjoy it at home or during your time in Japan.
In 2025, the event falls on two days—Saturday, July 19 and Thursday, July 31. This double celebration happens when the 18-day Doyō period aligns with two “Ox” days, giving you twice the chance to enjoy unagi and recharge amid Japan’s hottest season.
What Is Doyō no Ushi no Hi?
Doyō no Ushi no Hi typically falls in late July, during the hottest stretch of the Japanese summer. The term “Doyō” refers to an 18-day transitional period before the start of a new season—based on Japan’s traditional lunisolar calendar rather than the modern Gregorian one.
“Ushi” (ox) refers to one of the 12 zodiac signs, which is still commonly used in Japan for designating days. During each Doyō period, there is at least one “day of the ox”—and occasionally two—giving people a culturally-sanctioned excuse to indulge in unagi.
Why Eel? The History Behind the Tradition
So how did this all begin? And why do people continue shelling out the big bucks for this tasty treat?
As with many consumer traditions, its origins lie in a mix of practical advice and brilliant marketing. According to legend, a struggling eel shop owner in the Edo period (1603–1868) sought help from the famed physician and inventor Hiraga Gennai.
Gennai noted a custom of eating foods starting with the “u” (う) sound to ward off summer fatigue, and proposed a cleverly worded campaign: "Unagi no Ushi no Hi"—eel on the Day of the Ox. It was catchy, timely, and incredibly effective.
Since then, eating eel on this specific day has become a beloved seasonal tradition.
Popular Summer Foods That Start With “U”
While unagi is the star, it’s not the only food celebrated during this time. Other “u”-foods are believed to offer health benefits as well:
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Udon (うどん) – Thick, chewy noodles that are easy on the stomach.
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Umeboshi (うめぼし) – Sour pickled plums; great for hydration and digestion.
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Uri (うり) – Gourds like cucumber and watermelon, full of water and cooling properties.
In the Kansai region, some people also eat doyō-mochi, sweet rice cakes said to boost energy and bring good luck.
Summer Fatigue and Health Benefits
While rooted in folk wisdom, many of the foods eaten on Doyō no Ushi no Hi do provide real health benefits.
With temperatures often soaring past 35°C (95°F), summer in Japan can drain you faster than you can blink the sweat from your eyes. Appetite fades, fatigue sets in, and people naturally look for easy-to-eat, energy-rich meals.
Unagi fits the bill perfectly. It’s packed with protein, B vitamins, and omega-3 fatty acids that support the brain, skin, and immune system—making it an ideal midsummer pick-me-up.
How Japan Celebrates Doyo no Ushi no Hi Today
The modern version of Doyō no Ushi no Hi is celebrated with as much enthusiasm as ever. In the weeks leading up to the day, supermarkets begin advertising heavily, and unagi becomes readily available—even at discounted prices.
Traditionally, the eel is grilled and brushed with a sweet soy-based glaze, then served over a bed of fluffy white rice in a lacquered bento box. This dish is known as Unajū (a blend of unagi and jūbako, the lacquered box it’s served in).
Whether bought from a shop or made at home, it’s a seasonal favorite enjoyed by families all over Japan.
How to Make Unagi at Home
Want to try making your own Unajū at home? Here’s some simple tips to get you started:
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Broil or grill the eel over high heat (never bake), for 6–8 minutes.
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Baste occasionally with a sweet soy-based sauce (like kabayaki or teriyaki).
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Grill until you get a nice char—crispy edges without burning.
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Finish with one final dip in sauce and serve over warm white rice.
**Be generous with the sauce—this is where the flavor shines!**
If unagi isn’t in your budget, eggplant, whitefish, or even seasoned tofu can make great substitutes while still honoring the spirit of the dish.
Final Thoughts: Tradition in Every Bite
Whether you pick up unagi from your local grocery store or prepare it at home, Doyō no Ushi no Hi is a flavorful reminder of the ways Japan weaves tradition into everyday life.
It’s a holiday built around seasonality, shared memory, and rhythm—a perfect example of how food can connect people to the past while nourishing them in the present.
Curious about more Japanese traditions and seasonal events? Browse the rest of our blog for more cultural deep dives—and if you have questions or topic requests, feel free to reach out on social media or by email!
FAQ
Q: When is Doyo no Ushi no Hi in 2025?
A: In 2025, the holiday falls on July 19 and July 31.
Q: Why do Japanese people eat eel on Doyo no Ushi no Hi?
A: Because unagi is rich in nutrients and helps combat summer fatigue.
Q: I don’t like eel! What are some alternatives that I can eat?
A: Whitefish, eggplant, and seasoned tofu make for great alternatives!
Q: Where can I buy grilled unagi in Japan?
A: Unagi is available year round in grocery stores throughout Japan.
Q: What’s the best way to cook unagi at home?
A: Broil it on high heat for 6–8 minutes until slightly charred, then dip in sweet teriyaki or kabayaki sauce.