As US tariffs stimulate safe-haven demand, Japan's ultra-long government bonds recorded a record net inflow of foreign funds last month, highlighting their appeal as a safe-haven asset.

Global investors bought a net 2.18 trillion yen (about $15.5 billion) of Japanese government bonds with maturities of more than 10 years in March, a record high, according to the latest data released by the Japan Securities Dealers Association on Monday. The total net purchase of government bonds of all maturities reached 6.03 trillion yen, the second highest level since records began in 2004.

Since March, international funds' demand for Japanese government bonds has risen significantly as the Trump administration's tariff measures have caused sharp fluctuations in financial markets. Preliminary weekly data released by Japan's Ministry of Finance showed that the scale of foreign funds flowing into the Japanese bond market this month remained at a high level.

In contrast, local insurance companies sold a record net 645.8 billion yen of ultra-long government bonds in March. Data showed that the yield on 30-year Japanese government bonds rose to its highest level since 2006 in mid-March and climbed further this month, due to factors including the Bank of Japan's slowdown in buying super-long government bonds and the huge shock in the U.S. bond market that spread to global bond markets.