After a week of rapid increases, yields on Japan’s 30- and 40-year government bonds dropped more than 10 basis points in late trading on Friday.

Japan's super-long government bond yields have spiked to record highs, as mounting political calls for tax cuts and big spending draw investors' attention to the country's fiscal woes. The rise in yields complicates the Bank of Japan's (BOJ) quest to wean the economy off a decade-long stimulus programme including by slowing its huge bond purchases.

Japan's bond yield surge hints at global market risks. See how it impacts U.S. Treasuries, the yen, and top investments like Toyota and Sony.