What does it taste like?
Funazushi, prepared by chef Ohashi.
Kate Springer
At first glance, narezushi looks nothing like modern sushi. It's usually sold as one whole fish, covered in a goopy, yogurt-like sauce.
To serve, sushi chefs will slice the fish into thin layers and arrange them atop a bed of rice in a beautiful pattern.
Sometimes, they prepare narezushi as porridge with hot tea (called ochazuke-rice), or even fry it up like tempura.
But no matter how it's prepared, narezushi is one of those divisive foods that will either make or break your dinner because of the sushi's sewage-like aroma and mouth-puckeringly sour taste.
Of course, for connoisseurs, the stinkier, the better.
"The people who love funazushi, they really love it. The first time I tasted it, I was actually in high school, around 16 or 17 years old," says Ohashi.
"I thought it was really gross. But my father, who was also a chef, enjoyed these things. He put it in a soup for me, which I enjoyed much better."
While he couldn't quite stomach it at first, Ohashi says the taste has grown on him over time.
“If done properly, even the head can be fully consumed. That's the sign of a good funazushi”
"Now I enjoy it. Over time, the lactic acid and bacteria in the rice breaks down the fish and, if done properly, even the head can be fully consumed. That's the sign of a good funazushi," he adds.
"The technique is a thing to be proud of -- we are proud of making this sushi for 1,000 years. When you eat funazushi, you can feel the history."
To Ohashi's knowledge, the oldest funazushi has been fermented for a century.
"If it's 100 years old, it's still not rotten because of the fermentation," says Ohashi. "By that time, it wouldn't be much more than liquid."
The older it is, the rarer it is -- and old narezushi can cost hundreds of US dollars, though the most common types will have aged for about one year.