Japan is expanding efforts to attract buyers to the nation's growing debt load, flooding the backs of taxi cabs for the first time with pamphlets in the hopes of getting retirees to invest more money in bonds.

"Government bonds are worth another look," the Finance Ministry says in its latest advertisement, which features a picture of 37-year-old Junko Kubo, a former anchor on NHK. Individuals can buy government debt at local banks for as little as ¥10,000, according to the ads. The ministry is hawking the bonds on its Web site with the slogan, translated from Japanese, "Peace of mind. Piece of happiness."

"We are targeting those people with money for retirement," said Masaaki Kaizuka, director of debt management policy for the government in Tokyo.

Finance Minister Kaoru Yosano is borrowing record amounts to help pull the economy out of its deepest postwar recession, increasing national debt to ¥684.4 trillion. Besides taxis, the government is putting posters in banks and planning ads for television later this year.

The ministry is spending ¥650 million on bond ads for the fiscal year that ends March 31, which is "slightly" less than in the prior 12 months, Kaizuka said.

Kubo follows the actress and model Koyuki, who appeared in ads for Japan bonds in 2003. That same year, Koyuki, who goes by one name, starred with Tom Cruise in "The Last Samurai." In 2002, the Finance Ministry hired kabuki actor Koshiro Matsumoto and model Norika Fujiwara for its bond campaigns.

Now Kubo is marketing bonds to the 17 percent of Japan's 127.3 million people who are over 65. Japan's so-called baby boomers, who were born from 1947 through 1949 and will start turning 65 in 2012, will have ¥80 trillion in pension funds to spend when they retire, government estimates show.

Households own ¥36 trillion of the nation's debt, or about 5 percent of the market. Their ownership has doubled from ¥18 trillion five years ago, while holdings of stocks have fallen to ¥79.7 trillion from ¥205.8 trillion in 2007, Bank of Japan figures show.

Japan's benchmark 10-year bond yields 1.34 percent, the lowest among 31 countries ranked by Bloomberg and compared with 3.43 percent for U.S. Treasuries.

The 10-year floating-rate bond for individuals that was issued last month and matures in July 2019 yields 0.73 percent, according to data compiled by Bloomberg. Three-month bank deposits in Japan pay an annual rate of 0.35 percent.

"The yield is higher than what you get at the bank," said Yasutoshi Nagai, a 46-year-old economist in Tokyo who purchased floating-rate bonds a few years ago. "It's not so bad."

The taxi ads offer "guaranteed rates," with a floor of 0.05 percent, even if market rates fall below that, in line with the government's efforts to focus on the safety of its debt.

Japan has the world's biggest government bond market and the United States is No. 2, based on a ranking of 35 nations by the Bank of International Settlements in Basel, Switzerland.