The Eel Japan Built an Entire Summer Tradition Around

Learn how unagi is grilled, why Kanto and Kansai prepare it differently, what the midsummer Day of the Ox is about, and how to enjoy eel on a trip.

Updated October 19, 2026 | By Tokyo Paul

Quick answer: Unagi is freshwater eel, most often the Japanese eel, split, grilled and usually brushed with a sweet soy-based sauce in a style called kabayaki. It is served over rice and is closely tied to Doyo no Ushi no Hi, the midsummer Day of the Ox, when eating eel is a long-standing custom for keeping up stamina in the heat.

What unagi is and where it fits in Japanese food

Unagi is the Japanese word for freshwater eel, and in everyday use it means the Japanese eel (Anguilla japonica). It is a long, smooth, scaleless fish with rich, tender flesh and a naturally high oil content, which is why it takes so well to grilling over charcoal. Saltwater eel is a different animal called anago, which is milder, softer and usually lighter in flavor.

In Japan, eel is treated as a special-occasion food rather than a casual daily meal. Specialist eel restaurants often focus on nothing else, and a bowl or box of eel on rice is seen as a treat, a restorative meal and a classic summer dish. Eel is also widely sold at supermarkets and department store food halls, especially in the weeks leading up to midsummer.

Raw eel is not eaten. The blood of freshwater eels contains a protein toxin that is broken down by heat, so unagi is always cooked through, whether grilled, steamed or simmered. This is one reason the long, careful grilling that eel restaurants are known for is more than a flavor choice.

Kabayaki and shirayaki: the two classic ways to grill

The most famous preparation is kabayaki. The eel is split open, boned, cut into fillets and threaded onto skewers, then grilled and brushed repeatedly with tare, a sweet and savory sauce built on soy sauce and sweetener. The sauce caramelizes on the surface, giving the glossy, lacquered look and deep aroma that many people associate with a good eel shop. Many restaurants keep their tare going for a very long time and treat it as a point of pride.

The second classic method is shirayaki, which means roughly "white grilling." The eel is grilled with only a little salt and no tare. Without the sweet glaze, the natural flavor of the fish and the smoke from the charcoal come forward. Shirayaki is often eaten with a touch of freshly grated wasabi or a little soy sauce, and it is a popular way to taste the eel itself.

The grilling method also explains why a good eel meal takes time. Many shops prepare each fish after the order is placed, so a wait of around half an hour is not unusual in specialist restaurants. Order times vary, so allow extra time in the schedule, and expect a relaxed pace rather than a quick bite.

Kanto and Kansai: two regional styles

Eel preparation is one of the clearest examples of eastern and western Japan doing things differently. In the Kanto region (the Tokyo area), the eel is usually cut open along the back. The fillets are first grilled plain, then steamed, and finally brushed with tare and grilled again. Steaming softens the flesh and removes some of the fat, which produces a fluffy, delicate texture.

In the Kansai region (the Osaka area), the eel is traditionally cut open along the belly. It is grilled without a steaming step, often in a long piece rather than cut into portions. The result is firmer, with a crisp surface and a stronger grilled flavor. Some cooks layer the eel between hot rice to soften the skin as it is served.

A common explanation for the difference is cultural: in the old samurai city of Edo, cutting along the belly was said to resemble seppuku, so cooks cut along the back instead, while the merchant city of Osaka had no such concern. Treat this as a popular story rather than a settled fact. Either way, travelers who try eel in both regions can enjoy a real contrast in texture.

Doyo no Ushi no Hi: the midsummer Day of the Ox

Doyo no Ushi no Hi is the traditional "Day of the Ox in the doyo period," a stretch of days before the start of autumn on the old seasonal calendar. The days in this cycle are named after the twelve zodiac animals, and an ox day that falls in the hottest part of summer is the one linked to eating eel. The date changes from year to year and usually falls between about mid July and early August, so check a current calendar for the exact day.

The custom is generally traced to the Edo period (1603 to 1868), when eel was believed to help people keep their strength through the heat. Eel is rich in fat and protein, and the idea of eating something nourishing to get through the humid season fits a wider Japanese habit of seasonal foods. Kabayaki is the classic choice, though other dishes are also eaten on the same day.

A well-known story credits Hiraga Gennai, an Edo-period polymath, with helping an eel shop that was struggling in summer, the traditionally slow season for eel. He is said to have suggested a sign linking eel to the Day of the Ox. The tale is widely repeated, but it is better understood as a popular legend than a documented event.

How eel appears on a menu

Most visitors meet eel as unadon or unaju. Unadon is sliced kabayaki laid over a bowl of steamed rice. Unaju is the same idea served in a lacquered box, called a jubako, and it is often a step up in portion and presentation. Many restaurants offer several grades of the same dish, usually based on how much eel is included, so look for the number or tier printed on the menu.

In the Nagoya area, a local specialty called hitsumabushi is popular. Chopped, grilled eel is served over rice in a wooden tub, and diners are typically guided to eat it in several stages: first plain, then with condiments such as green onion and wasabi, and finally as a soup-like dish with hot broth poured over. Menus often explain the steps, so it is easy to follow.

Other eel dishes include kimosui, a clear soup made with eel liver, and umaki, a rolled omelet wrapped around grilled eel. Lake Hamana in Shizuoka Prefecture has long been associated with eel farming and is widely known for unagi, so travelers heading along the Tokaido route sometimes plan an eel meal there. Check current information on opening hours and any reservation needs.

Why eel is a sustainability topic

The life of the Japanese eel is unusual. Adults travel thousands of kilometers to spawn in the western North Pacific, and their transparent, leaf-shaped larvae drift back toward East Asia on ocean currents. They arrive at coasts as glass eels, move into rivers and live as yellow eels for several years, and later become silver eels that head back to sea. Because of this biology, eel farming has long relied on young wild eels caught in rivers.

The species is classified as endangered, both on the IUCN list and by Japan's Ministry of the Environment. Wild numbers have fallen over the past several decades because of overfishing, habitat change, and shifts in ocean conditions. In response, Japan has introduced permit systems for catching and farming eel, and researchers have worked for decades on raising eel through a complete life cycle in captivity.

That research has produced results. Laboratory hatching was first achieved in 1973, and induced spawning from captive-raised adults followed in 2010. In 2026, a large retailer was reported to have begun selling kabayaki made from fully farmed eel, described as trial sales, and the cost remains higher than for conventional farmed eel; check current news for availability. Visitors who want to eat eel responsibly may choose smaller portions, enjoy it for special occasions, and consider other summer dishes on ordinary days.

Tips for eating eel as a visitor

Timing matters. The days around Doyo no Ushi no Hi are busy, and eel shops can have long lines, so arriving early or booking ahead (where reservations are accepted) helps. Many places also run out of eel and close for the day, so visit before the usual lunch peak if possible.

On the table, a small packet or shaker of sansho (Japanese pepper) is often provided. It is traditionally sprinkled over kabayaki because its citrusy, slightly numbing taste balances the rich sauce. Eel bones are mostly removed, but tiny bones can remain, so eat attentively. The skin and the glazed edges are considered part of the enjoyment.

Prices vary a great deal by restaurant, grade and season, and eel has become more costly as supply has tightened, so check current menus. Travelers with allergies or dietary needs should ask staff about ingredients in the tare. This guide shares general cultural information and published research, not professional advice; for health questions, talk with a doctor.

Frequently Asked Questions

Is unagi eaten raw in Japan?

No. Freshwater eel is always cooked, because its blood contains a protein toxin that is destroyed by heat. Eel is commonly grilled, steamed or simmered, and it is served hot or warm. Dishes that look like sushi use cooked, glazed eel rather than raw fish. Anago, the saltwater eel, is also served cooked.

What is the difference between unagi and anago?

Unagi is freshwater eel, usually the Japanese eel, and has a rich, fatty, bold flavor that suits the sweet tare used in kabayaki. Anago is a saltwater conger eel with a lighter, softer and more delicate taste. Anago is often simmered or grilled and used in sushi and tempura, while unagi is typically served over rice.

When is the Day of the Ox for eating eel?

Doyo no Ushi no Hi falls during the hottest stretch of summer, usually between mid July and early August, and the exact date changes each year. Check a current Japanese calendar or news source for the date. Shops often take advance orders for eel before the day, so planning early is wise.