Please note: Reservations are required; walk-ins cannot be accommodated.
Please note: Reservations are required.
Hello, I’m Fujito, head sushi chef at REONA Sushi Tokyo.
Today, I’d like to introduce one of the most luxurious toppings in the world of sushi—uni, or sea urchin.
In Japan, uni is a prized ingredient often featured as a highlight of an omakase course. Its rich sweetness and melt-in-the-mouth texture leave a lasting impression. Personally, I believe the quality of uni can make or break the overall impression of a sushi course.
That said, in serving guests from all over the world, I’ve encountered a few who say they don’t enjoy uni. For some, it’s the appearance. For others, it’s the flavor. But in many of those cases, I’ve seen their opinions change dramatically once they’ve tasted truly high-quality uni.
You see, the taste of uni varies significantly depending on its origin and handling. It’s an incredibly delicate ingredient that requires expert care and a discerning eye.
In this article, I’ll share why uni is one of my personal favorites—and why it may just become yours, too. If you’ve been hesitant to try it, REONA might be the place to change your mind.
Source:The National Museum of Emerging Science and Innovation
Uni is considered a premium delicacy in Japan, and domestically harvested uni rarely reaches overseas markets.
Its allure lies in the luxurious sweetness, deep aroma, and silky texture—uni is truly a feast for the senses.
Among a sushi lineup dominated by fish, uni stands out as a uniquely expressive topping.
Despite its spiky appearance, sea urchin flesh is soft and fragile, making it one of the most delicate ingredients to handle. While uni can be harvested across Japan, its flavor varies greatly by region. In fact, the waters around Tokyo don’t produce particularly tasty uni.
That’s why, when Edo-style sushi first emerged in the early 19th century, uni was not a common topping.
It wasn’t until around 100 years ago that the now-famous gunkan-maki (battleship-style roll) was invented by the legendary founder of Ginza Kyubey. This innovation made it possible to serve uni as sushi, and the method spread rapidly.
Thanks to advancements in transportation and refrigeration, fresh uni from Japan’s best regions began arriving in Tokyo, elevating uni to a star ingredient in Edo-style sushi.
Even today, it remains a challenging ingredient—but precisely because of that, we sushi chefs handle it with the utmost care and pride.
There are several varieties of uni used in Edo-style sushi, each with its own flavor and character.
Although it’s all simply called “uni” on the menu, what you’re served can differ depending on the season. Few people realize that visiting the same sushi restaurant at different times of year can offer completely different uni experiences.
・Small in size, but intensely sweet
・Deep orange color with striking visual appeal
・Commonly found in colder waters like Hokkaido and Rishiri
・Highly popular as a sushi topping
・Larger grains with a smooth, creamy mouthfeel
・Mild and elegant flavor
・Sourced from warmer coastal regions like Honshu
・Versatile for use across many Japanese dishes
・A rare variety harvested in Kyushu and the Japan Sea
・Noted for its bold sweetness and rich aftertaste
・Deep reddish hue
・A favorite among connoisseurs due to its scarcity
Even within the same variety, the taste of uni can vary dramatically. What causes this difference? Two things: origin and storage method.
At REONA, and other Edo-style sushi restaurants, we pay special attention to these factors when sourcing uni.
In my opinion, the biggest factor affecting uni’s flavor is how it’s distributed.
Because uni spoils quickly, frozen uni is widely used—even at many sushi restaurants.
But here's the issue: uni is over 70% water. When frozen, the water inside expands into ice, rupturing the delicate cell walls that hold its flavor. As the uni thaws, its essence literally leaks away.
Even with modern freezing technology, frozen uni still suffers from texture and flavor loss compared to fresh uni. Especially when imported from overseas, the freezing process almost always diminishes its original quality.
That’s why frozen uni is often used at conveyor-belt sushi chains, mid-range establishments, or in countries where uni isn’t part of the culinary culture.
But I suspect this is one of the reasons some people believe they “don’t like uni.”
And that’s unfortunate.
At REONA, we exclusively use fresh, domestic uni sourced from top regions in Japan.
If you’ve had a negative impression of uni in the past, I urge you to try fresh uni sushi in Japan. It might just become one of your favorite sushi experiences.
Source:Okushiri Island Tourist Association（https://unimaru.com/wordpress/wp-content/uploads/2016/07/a1348a4a5bec80d2bf418de010911dbe.jpg）
Origin matters too—and in Japan, Hokkaido uni is widely regarded as the best.
Why? The flavor is rich and clean, with a lingering umami finish that pairs beautifully with vinegared rice.
The secret lies in the diet of Hokkaido uni.
The waters around Hokkaido are famous for high-quality kombu (kelp), which is rich in glutamic acid—the same compound responsible for umami in Japanese cuisine.
Uni raised on this kombu absorbs its flavors, producing a naturally sweet, deeply savory uni that’s worlds apart from average varieties.
So when you taste Hokkaido uni, you’re not just enjoying the product of careful harvesting—you’re experiencing the result of an entire marine ecosystem working in harmony.
At REONA, you can watch the entire uni sushi process right before your eyes.
Our bilingual staff will walk you through every step, and you’re welcome to ask me questions directly if you're curious.
Handling uni requires extreme care. Everything from humidity to temperature to touch can affect its flavor and texture.
At REONA, we use dedicated chopsticks when working with uni to avoid crushing it. Too much pressure ruins its melt-in-the-mouth texture. Even prolonged hand contact can degrade its taste due to body heat.
That’s why shaping uni sushi demands both speed and delicacy—it’s one of the most nerve-wracking moments for any sushi chef. Freshness is also crucial, so the time between sourcing and serving is tightly controlled.
The most common way to serve uni is as gunkan-maki. Wrapped in a belt of seaweed and topped with uni, this style creates a vivid visual contrast between golden uni and black nori.
The combination of top-grade seaweed, fresh uni, and perfectly seasoned rice can elevate this one bite into a true work of edible art.
Flavor-wise, it’s wonderfully versatile. You can enjoy it rich with soy sauce or clean with just a sprinkle of salt.
Uni nigiri, on the other hand, forgoes the seaweed and places uni directly on top of a rice ball.
This minimalist presentation is beautiful but technically demanding. Apply too much pressure and the uni collapses. Not enough, and it slides off.
While this style showcases a chef’s technical skill, at REONA we usually serve uni as gunkan-maki to provide a more traditional Edo-style experience.
Uni sushi is more than just a luxurious delicacy—it’s a full sensory and cultural experience.
At REONA, we offer a special tasting opportunity where you can compare “standard-grade” and “top-grade” uni side by side. Don’t worry—this comparison piece is complimentary and not counted among your course items.
With detailed explanations from our English-speaking staff and the chance to observe sushi-making up close, you’ll gain more than just a meal—you’ll gain understanding.
Located in Kanda, a historic district at the heart of Tokyo’s sushi culture, REONA is the perfect place to immerse yourself in the artistry, tradition, and depth of uni sushi.
Whether you’re a longtime fan or someone who’s been unsure about uni, I sincerely hope your visit to Japan and to REONA helps you discover a whole new appreciation for it.
