Although Japan's outstanding public debt has edged down slightly from a record high, the decline was due to a one-off event that prevented it from blowing out even further, the Finance Ministry said Thursday.

The Japanese government's outstanding debt totaled 643.76 trillion yen as of June 30, down 25 trillion yen from the record 668.76 trillion yen on March 31, it said. The figure translates into a per capita debt of 5.04 million yen.

The decline occurred because Japan Post assumed some of the nonbond borrowings from state coffers when it was launched April 1, taking over the Postal Services Agency's mail delivery, postal savings and life insurance services. If the public corporation had not taken over the roughly 49 trillion yen in nonbond borrowings, the total outstanding public debt would have grown by about 24 trillion yen as of the end of March.