Sea urchin is one of the top three delicacies in Japan along with mullet roe (Karasumi), and cured sea cucumber intestines(Konowata). Sea urchin sushi uses the gonads of the sea urchin. The colors range from yellow to bright orange. This sushi was unavailable until the ship roll was invented, since it was too soft to make into a nigiri. Before the ship roll was invented, they were simply topped on rice placed in a bowl along with some condiments and enjoyed as a whole meal.
Sea urchin has a strong ocean scent, and it is very creamy and rich. It is prepared as a ship roll or gunkanmiaki, however some people prefer not to use nori for the ship roll and ask to be rolled with paper thin Japanese cucumber strips. The main reason for this is that seaweed has another kind of different ocean scent and it competes with the sea urchin. Using cucumbers instead makes it possible to taste the whole sea urchin. Quail egg is often placed inside the ship roll, but it is not recommended for it kills the flavors of the sea urchin. It should be used only if you want to weaken the aromas of the sea urchin.
Recently, many chefs have begun to make the sea urchin nigiri by tightening the flesh with cirtus juice. This slighly constricts the flesh so it is possible to make it into a nigiri style, and it is condidered the best way to eat sea urchin sushi.
When seasoning the sea urchin sushi, a few drops of soy sauce should be applied on top of the sea urchin directly from the soy sauce dispenser.