Below the strip lights, groups of middle-aged men in overalls and rubber boots are prodding and pinching at hundreds of silvery-white objects lined up in rows across the concrete. They look like frosty torpedoes or mysterious pods from outer space. A thin steamy vapour rises from them, and there are yellow labels stapled to their fins.
At six o'clock exactly a bell is rung, and the din redoubles as everyone in the shed starts simultaneously shouting and gesticulating. Strings of numbers and names can be heard; a man with a pot of red goo moves among the silvery torpedoes and brushes an elegant character on to the side of each. They are deep-frozen blue-fin tuna, the most esteemed of all Japan's many fish, and this is the daily auction at Tsukiji fish market, the place where sushi comes to die.
There is nowhere else quite like this in the world: in a good year 850,000 tonnes of fish - much of it still wriggling and thrashing - is hauled up on to the quayside on this eastern edge of Tokyo and laid out for auction in the shed alongside it. Like a medieval market, an entire community of suppliers has grown up around the trade, selling knives, hooks, boots, weighing scales, gloves and the tonnes of ice the market gets through every day. It is a spectacle of noise and colour, as aproned men drag carts bearing buckets of fish: the delicious, the repulsive and the weird. But beneath the surface much has changed in Japan during the past year and Tsukiji, like the rest of the country, is in a state of anxiety.
In any recession, food is the last thing people stop buying and, as the world's greatest piscivores, there is no danger the Japanese are going to stop eating fish. By the standards of recent European slumps, or by the economic crisis devastating south-east Asia, the hardship here is difficult to pin down - for though the economic figures show an economy unquestionably in decline, Tokyo still looks and feels one of the most prosperous cities on earth.
The point is that Japan's fall has been from heights so lofty that they appear, looking back, like a dream. At the height of the famous Bubble Economy, the Japanese were spending at such a level that ideas of what was normal and sustainable were lost. The tuna sellers of Tsukiji were the beneficiaries, and then the victims, of this bizarre period.
Of all the elements of the auction, the most important part is that which precedes the opening of the bids - the poking and caressing of the fish by the tuna buyers. "You see, tuna are all different like people," says Osamu Takahashi, who has been doing the job for 16 years. "And it all comes down to the amount of fat."
The lean, red, tuna sells in the auction for as little as 1,000 yen (pounds 5) a kilogram - even after the numerous middle men and transporters have added their mark up. This translates into something that the average family can afford to eat at home.
But it is the pale, pink toro - with its layers of sweet marbled fat - which Mr Takahashi tries to identify and which, even to the wholesalers, costs 10,000 yen (pounds 50 ) a kilo or more.
Fatty blue-fin tuna - served as sushi, rolled with rice, seaweed and even gold leaf - was the food of the Bubble Economy. It was consumed by executives on expense accounts and at top-class restaurants called ryotei. There an evening of food and sake, served by hostesses, routinely cost a few thousand pounds. But in the recessions, expense accounts at the ryotei were the first luxuries to go.
"The prices are about the same, but sometimes half the fish are unsold," says one Tsukiji stall-holder. "It's the politicians who used to go to the ryotei. They just aren't spending anymore."