TOKYO (Reuters) - Gobbling down a huge sushi roll in one go on Japan's February 3 end-of-winter festival is thought to bring good fortune -- just as long as you don't speak while you eat and remember to face the right way.
"Ehomaki," or "Lucky Direction" sushi rolls, are mammoth versions of the toothsome, seaweed-wrapped rice rolls that are a popular part of sushi meals. Roughly 6 cm (2.3 inches) in diameter and 20 cm (8 inches) long, they contain everything from egg, fish and vegetables to slices of fried pork cutlet.
The important thing is to take them in hand and eat, silently, while facing the proper direction -- this year, north-northwest.
Nobody really knows why or how the tradition evolved, though, only that it seems to have first appeared in the western city of Osaka.
"One of the theories for where Lucky Sushi Day came from is, well, men would make prostitutes in Osaka eat large sushi rolls and they'd watch that for a laugh," food analyst Minako Murakoshi told Reuters.
"There's some evidence for that but of course there are other theories as well."
A more likely explanation is that they were first whipped up by food stalls in Osaka in the mid-1800s. Then, a century later, a local seaweed retailer turned that into a regional tradition through sushi-eating contest and prizes for the largest sushi roll as a way to kick-start sales.
In more recent years, they've been seized upon by Japanese convenience store chains as a seasonal money spinner to fill the gap between Christmas and Valentine's Day.
Prior to this, February 3 -- or Setsubun -- was celebrated mainly by people throwing beans to chase demons out of their house, chanting "Out with demons, in with happiness."
But in 1989, retailer Seven Eleven launched a Lucky Sushi Day at one of its Osaka-area stores. The celebration was rolled out nationally in 1998.
"The Japanese are pretty keen on events associated with the seasons, like eating cake at Christmas or giving people chocolates on Valentine's Day," Murakoshi said.
"After Lucky Sushi Day, there'll be loads of chocolates for Valentine's Day out on the shelves, and consumers will be pulled in by that and end up buying lots of chocolates too."
At the top of Tokyo Tower, a popular tourist spot resembling the Eiffel Tower, people gathered to eat Lucky Sushi -- and struggled to say why.
"I think the tradition originally came from western Japan, but it's been promoted in all sorts of ways in Tokyo. Gradually everyone's started doing it," said Keiko Fuji, a Tokyo mother.
Others had more mundane concerns, such as how to actually eat the massive rolls.
"We cut it into smaller pieces and eat it that way," said 65-yea-old Yasuhiro Irie.
Traditionally, Lucky Sushi were filled with seven lucky ingredients, including egg, cucumber and eel. But the modern version includes some stuffed with spongecake, or even with bread in place of rice.
Editing by Elaine Lies, editing by Paul Casciato