In many ways, Botswana is an African success story, boasting the world's fastest-growing income per capita over the past 35 years.

But this has done little to stop Japanese politicians from dismissing its achievements or picking on its problems.

Ever since Moody's Investors Services Inc. downgraded Japan's sovereign credit rating to a notch lower than that of Botswana, the southern African nation has been a favorite target for Japanese politicians striving to discredit the U.S. credit rating agency.