As bartenders close the shutters in Tokyo's glitzy nightlife district, just a short walk away handbells ring in the pre-dawn tuna auctions in an old warehouse in Tsukiji.
Veteran auctioneers call for bids for hundreds of snap-frozen tuna laid in neat rows in the world's largest fish market, the size of more than 40 football pitches.
The ocean predators, steaming dry ice, have their tails cut to reveal oval windows of the burgundy flesh that has fetched as much as 175,000 dollars for a 232 kilogram (511 pound) fish here.
In the chilly halls, fishmongers with headbands and aprons slice the red flesh with large knives, while three-wheel trolleys race through the warren of narrow aisles.
The famous market on Tokyo Bay, long a must-see tourist spot, is facing a disputed relocation plan in coming years - but another threat is looming large, a possible cross-border trade ban on Atlantic bluefin tuna.
At a meeting in Doha, Qatar that runs until March 25, countries will vote on whether to declare Atlantic bluefin a highly endangered species, alongside tigers, great apes and the panda, and ban its international trade.
A ban became more likely after the United States and the European Union last week backed the move ahead of the meeting of the Convention on International Trade in Endangered Species (CITES).
Decades of overfishing have seen stocks crash by more than two-thirds in the Mediterranean, from where giant freezer ships have long headed for Japan, which consumes three-quarters of the global bluefin catch.
But the move has sounded alarm bells in Japan.
"I can't imagine sushi without tuna," said Ayaka Mimura, a 21-year-old Tokyo university student, as she was buying seafood in Tsukiji.
"Of course, I oppose overfishing. But a sudden, total ban sounds unfavourable to me. We just eat fish the way others eat beef."
It is a view shared by Japan's government and fishing industry, who oppose and have threatened to ignore a trade ban, pushing instead for industry-based ways to make the catch more sustainable.
Japan last year pledged to help meet an accord to slash the total catch in the eastern Atlantic and Mediterranean by 40 percent, although environmental groups charge that such quotas are routinely exceeded.
"Overfishing has never ended under the current quotas," said Wakao Hanaoka, a Greenpeace researcher. "It is necessary to protect the fish under the convention. I hope Japan will take responsible action."
Hisashi Endo, a Fisheries Agency official, said: "We are not optimistic about the meeting. We are concerned the result could set a new global trend and spread to the Pacific and other oceans."
Vice fisheries minister Masahiko Yamada has already hinted Japan will opt out of a ban by taking a so-called "reservation", as it has done on whale species in the past.
Tokyo will dispatch Fisheries Agency chief Katsuhiro Machida to Qatar on Tuesday to head its delegation and lobby for support.
Japan sources 25,000 tonnes of bluefin tuna a year from the Pacific and 19,000 tonnes from the Atlantic. The country also has about 20,000 tonnes of deep-frozen bluefin tuna in domestic stock.
Yuichiro Harada, who works with a Tokyo-based lobbying group that says it supports "responsible" bluefin tuna fishing, said: "It's quite unfair to treat tuna the same way as lions and tigers and elephants.
"Unlike those animals, tuna can bear hundreds of millions of eggs and is internationally recognised as a commercial food."
Tsukiji fishmongers staged a small protest last week, yelling out "Protect tuna in the markets!" and "We oppose a decision at the Washington Convention" as the CITES treaty is also known.
Traders fear a steep price hike for the bluefin, known as "kuro maguro" or black tuna in Japan. A piece of "otoro" or fatty underbelly, now costs 2,000 yen (22 dollars) at high-end Tokyo restaurants.
"I bet prices will jump on the same day if the ban is adopted," said Mitsunobu Iida, a tuna wholesaler and sushi restaurant owner.
"That's what market sentiment is always like. We can't ask our customers to accept a price hike easily.... If we raised the price, people would stop buying it. I'm afraid we are going to have a hard time."Reuse content