The value of publicly placed trust funds, which are largely targetted at retail investors, rose 1.3 trillion yen or 2.7 percent to 51.5 trillion yen ($513.2 billion) in March from 50.1 trillion yen the previous month, data from Japan's Investment Trusts Association showed.
The recovery in global stock prices and the fall in the yen helped boost the overall value despite seeing a slight net fund outflow of 6.5 billion yen in March, Katsuhiro Konishi, the association's secretary-general, told a news conference.
Tokyo's Nikkei average .N225 rose 7.1 percent and the broader Topix .TOPX rose more than 2 percent during the month.
A broad fall in the yen helped lift the value of foreign-currency denominated funds.
The yen rose 0.4 percent against the dollar and 4.5 percent against the euro in March from the previous month, Konishi said.
The value of stock investment trust assets, which make up 78 percent of the total, rose 1.4 trillion yen or 3.6 percent to 40.4 trillion yen in March from the month before.
The value of privately placed investment trust funds, which are mainly bought by institutions, rose 1.1 percent to 24.8 trillion yen in March.
Meanwhile, Japanese investment trust holdings of foreign assets -- stocks, bonds and money market instruments -- rose by 880 billion yen to 22.6 trillion yen, the association said.
Foreign stock investments rose by 277 billion yen to 3.76 trillion yen in March, making up 16.6 percent of total overseas asset holdings.
Foreign bond holdings rose by 510 billion yen to 16 trillion yen, making up 70.5 percent of total holdings. ($1=100.34 yen) (Reporting by Chikafumi Hodo; Editing by Chris Gallagher)