But wholesalers at the sprawling complex in Tokyo's Toyosu neighbourhood are battling a long slump.

Demand for fresh fish, especially the prized bluefin tuna, has collapsed.

That as consumers steer clear of bars and restaurants over health worries.

Trader Kimio Amano says businesses like his are on the brink:

"Sales slumped 90% in April and May during the state of emergency, to a point where I had no work. I've recovered slowly after that but sales are still down 30 to 40% and I'm barely scraping through."

Dealers had hoped for recovery after Japan lifted its state of emergency in May.

But big events like weddings and shareholder meetings remain on hold.

And it's still slow going for bars and restaurants.

Yasuyuki Shimahara owns a traditional Japanese-style pub in Tokyo.

He says business is down 60% compared to this time last year.

That's forced him to innovate.

Since customers won't come, he says, he's doing online orders for frozen tuna instead.

But Japanese like their raw fish fresh, not defrosted.

And traders says increased demand for home eating has not filled the gap left by restaurants and events.

Now the fallout will be felt by fishermen far beyond Tokyo.

Japan is the world's biggest buyer of tuna, but this year its imports are down by almost a fifth.