What Is Uni? Types, Seasons, and 5 Recommended Sushi Restaurants in Tokyo

What Is Uni?

Uni: A Close Relative of Starfish

Uni is a type of echinoderm that lives in the ocean, known for its round, spiny shell. It belongs to the same family as starfish. The part we eat is the sea urchin’s immature gonads-either the testes or ovaries—which are nearly identical in both appearance and taste, making them difficult to distinguish.

Uni has been a culinary staple in Japan, Korea, and parts of Europe for centuries. In the United States, however, it was not traditionally popular. But with the rise of Japanese cuisine worldwide, more people in the U.S. have developed a taste for uni in recent years.

Types of Uni

There are over 800 species of sea urchins worldwide, but only about six are commonly eaten in Japan:

Murasaki Uni (Purple Sea Urchin)

Known for its yellowish roe and rich, intense flavor.

Kita-Murasaki Uni (Northern Purple Sea Urchin)

Has a mild, slightly sweet taste, making it a popular choice for sushi.

Bafun Uni (Horse Dung Sea Urchin)

Small but packed with a strong umami flavor, often used in processed uni products.

Ezo-Bafun Uni (Hokkaido Horse Dung Sea Urchin)

Features bright orange roe with a sweet, concentrated taste.

Aka Uni (Red Sea Urchin)

Extremely rare and often called the “phantom uni.” Highly prized for its strong sweetness and exceptional flavor.

Shirahige Uni (White Beard Sea Urchin)

Native to Okinawa and southern Japan, it has a light, refreshing taste but is not commonly eaten.

The Season for Uni

The season for uni varies by species, but generally, it runs from June to August. During this time, the reproductive organs of the uni mature, bringing out its best flavor.

Famous Uni-Producing Regions in Japan

In Japan, uni from Hokkaido is particularly renowned. The main types of uni harvested there are Kitamurasaki Uni and Ezo Bafun Uni, with Kitamurasaki Uni being especially popular as a sushi topping. Hokkaido uni thrives in cold waters and feeds on abundant kelp, which results in firm flesh and a rich, flavorful taste.

Where to Eat Uni in Japan

Uni is considered a luxury food in Japan, so it's not something people typically eat every day. At high-end sushi restaurants, you can savor fresh, top-quality Japanese uni. However, you can also find uni at conveyor-belt sushi or more casual sushi spots. The ability to offer premium uni at lower prices is due to advancements in technology and business efforts. Uni that doesn't use myouban (calcined alum) lets you experience its pure, natural flavor, though it can be challenging to preserve. Since it’s usually served at upscale restaurants, if you want to enjoy the true taste of uni, it’s best to visit a high-end sushi spot.

Uni Sushi

Uni sushi is typically served as gunkan-maki (battleship roll). This style was created by the chefs at Ginza Kyubey, one of Japan’s most famous sushi restaurants. It consists of vinegared rice wrapped in seaweed, topped with uni. However, some sushi chefs feel that the seaweed can overpower the uni's delicate flavor, so they may serve it as sushi instead.

For the best uni experience in Japan, it's recommended to visit a high-end sushi restaurant.

Where to Find Delicious Uni at Sushi Restaurants in Tokyo

Udatsu Sushi （宇田津 鮨）/ Sushi

Selected Restaurant

Michelin Guide, 2025

This sushi restaurant, built around the concept of "Art x Sushi," is extremely popular with foreigners. The atmosphere is calm and refined, and the dishes are true works of art. The uni sushi here features both bafun uni and murasaki uni, served lavishly with a special seaweed accent carefully chosen by the chef. It's a visually stunning and flavorful dish that delivers the best of both worlds.

Sushi Kakizaki （すし柿崎）/ Sushi

Located in Ningyocho, this hidden gem is run by a husband-and-wife team. The chef, who has worked in the sushi departments of luxury hotels, prepares a course of appetizers and sushi using seafood directly sourced from the Toyosu market. Despite its price, the course offers a wide variety of dishes and delivers great satisfaction. A standout experience is the signature uni tasting, where you can compare bafun uni and murasaki uni—a truly luxurious experience.

Sushi Rizaki nishiazabu （鮨利﨑 西麻布）

Sushi Nagashima （鮨 長島）

Sushi Kitamura （鮨きたむら）