TOKYO - Nobody does Valentine's Day quite like the Japanese - more specifically, Japanese women.

While Feb. 14has been set aside as the day of romance in the U.S., Japanese tradition calls for women to give chocolates to men.

A sleek marketing campaign conjured up by Japanese confectioner Mary's chocolate reportedly started the custom in the 1950s. Fifty years later, the holiday has morphed into an all out celebration of chocolate in Japan, with women and social obligation driving half the annual $5 billion in sales.

"It's almost like a fifth season. It's that big," said Adam Kassab, a professor at Globis University in Tokyo. "The marketing people are very clever because they linked giving chocolates with a very core, cultural belief or value which is showing appreciation or social obligation."

The gift giving isn't limited to a significant other, but co-workers, friends, and family. The exchange even comes with its own etiquette rules, according to Kassab.

Cheaper chocolates given to male bosses and co-workers are dubbed "giri-choco" or "obligation chocolates."

"Anything below $10 is, they're not that special to you," Kassab said. "You just have to do it because everybody else does it."

The chocolate giving custom isn't cheap. A recent survey by department store Printemps Ginza found that women on average spend about $35 on chocolate for their significant other, and shell out more than $100 for obligation chocolates. They set aside $30 to buy chocolates for themselves, also known as "jibun choco."

"These days, I usually just buy [obligation chocolates] at the grocery store," Tamaki Takeuchi said, laughing. "For family, I make a cake to give to my grandpa."

There are plenty of alternatives for those seeking Valentine's Day experiences beyond a traditional box of chocolates.

Hotel Nikko in Odaiba began offering chocolate facials for a limited time while Tokyo restaurant chain Ramen Musashi served up chocolate noodles, dipped in mushroom whip cream soup and topped off with vegetables, chocolate coated ground pork, and rock candy.

At the Fab Café in Shibuya, women signed up to get 3D scans of themselves, to create chocolate molds of their faces.

"I thought it was odd when I first heard about it on Twitter, but I had to give it a try," said Takeuchi, who planned to give her chocolate doppelgangers to two of her younger co-workers.

Japanese men aren't entirely off the hook. While they may not have to give chocolates on Valentine's Day, they are expected to return the favor on their own manufactured holiday, a month from now - "White Day."