Unagi: Japan's Beloved Grilled Eel

A friendly guide to unagi, Japan's glossy grilled freshwater eel: how it is prepared, the classic dishes, the summer eel day and where to try it.

Published October 18, 2026 at 7:05 AM JST | By Tokyo Paul

Quick answer: Unagi is Japan's freshwater eel, usually grilled kabayaki-style and brushed with a sweet soy-based sauce, then served over rice as unadon, unaju or hitsumabushi. It is especially popular on Doyo no Ushi no Hi, the midsummer Day of the Ox.

Few dishes smell as irresistible as eel crackling over charcoal, brushed with a sweet-savory glaze until it turns lacquer-dark and glossy. That is unagi, the Japanese word for freshwater eel, and it has been a treasured treat in Japan for centuries. This guide explains what unagi is, how the classic kabayaki style works, the dishes you will see on menus, the famous summer tradition of eating eel, and how to enjoy it with confidence at a restaurant. By the end, you will know the difference between a bowl, a lacquered box and a Nagoya-style set, and you will understand why a bite of tender eel on warm rice feels like a small celebration.

What Is Unagi and How Is It Prepared?

Unagi refers to freshwater eel, most often the Japanese eel (Anguilla japonica), and it is a different fish from anago, the saltwater conger eel that often appears on sushi counters. The best-known preparation is kabayaki, in which the eel is split, skewered, grilled and repeatedly brushed with tare, a sauce built from soy sauce, mirin and sugar. The result is a tender, rich fillet with a lightly caramelized surface. A simpler style called shirayaki skips the sauce and grills the eel with only a little salt, which lets the natural flavor of the fish stand out. Eel is always served fully cooked, and a good restaurant often takes its time, so it is normal to wait a while after ordering.

Regional habits shape the final dish. In the Kanto region around Tokyo, eel is traditionally steamed before it is grilled, which softens the flesh and lets some of the fat escape. In Kansai, the region around Osaka and Kyoto, the eel usually goes straight onto the grill, giving a crisper skin and a chewier, richer bite. Traditionally, Tokyo-area chefs also split the eel along the back, while Kansai chefs cut along the belly. If you travel between the two regions, trying both styles is a fun way to taste the difference.

Unadon, Unaju and Hitsumabushi: What Are the Differences?

The three most common ways to eat unagi differ mainly in how the eel and rice are presented. Unadon (sometimes written unagidon) is sliced eel laid over rice in a bowl, a casual and satisfying choice. Unaju serves the same idea in a lacquered stacking box called a jubako, which feels a little more special and is often ordered for celebrations. In both cases, extra tare is drizzled over the rice, so every mouthful carries a sweet, smoky flavor.

Nagoya has its own showpiece called hitsumabushi, a signature dish of the Tokai region. It is eaten in stages: first plain eel and rice, then with toppings such as chopped scallion, wasabi, nori or mitsuba, and finally with dashi broth or green tea poured over the bowl to make a soothing chazuke-style finish. This three-step approach is often called tabekurabe, or eat-and-compare, and it lets one portion taste like three different meals. Diners also commonly sprinkle sansho, a citrusy and slightly tingly Japanese pepper, over eel to brighten the richness.

What Is Doyo no Ushi no Hi, the Eel Day?

Doyo no Ushi no Hi, often translated as the Midsummer Day of the Ox, is the day when many people in Japan make a point of eating unagi. It falls on an ox day (one of the days in the traditional zodiac cycle) within the doyo period, the stretch of roughly eighteen days that marks the hottest part of summer, and it usually lands in the second half of July. Some years have two ox days in that period, so shops sometimes celebrate twice.

A popular story traces the custom to the Edo period. An eel-shop owner worried about slow summer sales is said to have asked the polymath Hiraga Gennai for help, and Hiraga suggested a sign reading that today was the ox day, so eat eel. Customers flocked in, other shops copied the idea, and it grew into a nationwide habit. Another tradition holds that foods starting with the sound "u," such as unagi, are good luck on an ox day (ushi). Supermarkets and restaurants fill up with eel specials around that time, so it is a lively moment to see the dish in everyday life.

Where Can You Eat the Best Unagi?

Eel is available across the country, but a few places are especially associated with it. Hamamatsu in Shizuoka Prefecture is famous for unagi, and Lake Hamana nearby is regarded as the birthplace of Japan's eel farming industry. The Japan National Tourism Organization notes that locals are so fond of eel that Hamamatsu even sells eel-flavored treats, including a well-known sweet pie. Many specialist restaurants cluster around the lake and in the city, and a stop here pairs nicely with a rail trip between Tokyo and Kyoto.

Specialist eel restaurants, called unagiya, are found in nearly every large city, and some have been operating for generations. Department store restaurant floors and station buildings often include a reliable unagi counter as well, which is handy for travelers on a schedule. Nagoya is the place to try hitsumabushi in its home territory. If you want to eat well, look for a shop where the eel is grilled to order, because freshly grilled fillets tend to taste the best.

Tips for Ordering and Enjoying Unagi

Many unagiya offer several portion sizes or grades of the same dish, and the choice usually relates to how much eel sits on the rice rather than the quality of the preparation. A smaller portion is a fine way to try the dish for the first time. Ordering a set often brings a clear soup with eel liver (kimosui) and a few pickles, which round out the meal nicely. As with any popular meal, lunch can be busy near peak eel season, so a little patience or a reservation helps.

Eel is a species conservation groups watch closely, and Japan's Ministry of the Environment lists the Japanese eel as endangered, so many people treat unagi as an occasional treat rather than an everyday dish. Researchers have also made steady progress on raising eel entirely in captivity, which is encouraging news for the future. If you have dietary restrictions, remember that tare contains soy sauce, so check with the restaurant about allergies before you order. Prices and opening hours vary a lot between shops, so it is wise to check a restaurant's official site or listing before you go.

Quick Takeaways

Unagi is Japan's glazed grilled freshwater eel, usually prepared in the kabayaki style with a sweet soy-based sauce, and it appears as unadon in a bowl, unaju in a lacquered box, or hitsumabushi in Nagoya. Tokyo-area eel is traditionally steamed before grilling for a softer texture, while Kansai eel is grilled directly for a chewier bite. The Midsummer Day of the Ox, usually in the second half of July, is the best-known occasion for eating eel, and Hamamatsu and Lake Hamana are the regions most associated with it. Treat it as a special meal, order a size that suits your appetite, and enjoy the smoky, sweet aroma that makes this dish so beloved. Whether you try a quick bowl at lunch or sit down for a full lacquered box, unagi is a delicious doorway into Japanese food culture.

Frequently Asked Questions

What is the difference between unagi and anago?

Unagi is freshwater eel, usually the Japanese eel, and tends to be rich and fatty. Anago is saltwater conger eel, which is lighter and softer and often appears on sushi counters. They are different fish with distinct flavors and textures.

What is the difference between unadon and unaju?

Both dishes serve grilled eel over rice with sweet tare sauce. Unadon comes in a bowl and is the casual option, while unaju is served in a lacquered stacking box called a jubako and feels a little more special.

Why do people in Japan eat eel in summer?

Many people eat unagi on Doyo no Ushi no Hi, the midsummer Day of the Ox, which usually falls in the second half of July. A popular story credits the Edo-period scholar Hiraga Gennai with the idea, and eel is also seen as hearty food for hot weather.