Five a.m. in Tokyo's Tsukiji fish market: A Setagaya Ward sushi chef chooses a 4,800 yen box of sea urchin from North Korea over a 6,500 yen box shipped from Hokkaido.

"I usually choose the Hokkaido produce," he said. "But the North Korean fare looks good today.

"I have a group of young people coming in, and for them, price is more important. Plus they're less likely to know the difference."