The balance of shares bought on credit turned higher last week, snapping a five-week decline.
The outstanding balance of long margin positions on the Tokyo, Osaka and Nagoya bourses stood at 1.59 trillion yen at the end of the week, up 7.04 billion yen from a week earlier, according to a weekly industry report.
The explosive rebound in share prices in recent weeks prompted individual investors to move in.
The trigger for the surge was the Bank of Japan's decision at its March 19 policy-setting committee meeting to funnel more money into the beleaguered economy in an attempt to head off a deflationary spiral.
The BOJ has said it will retain the policy until consumer prices stabilize.
In terms of volume, the balance of long positions stood at 2.44 billion shares, up 61.63 billion for the fourth consecutive week of increase.
The average buying price, obtained by dividing purchase value by volume, fell from the previous week's 666 yen to 652 yen, suggesting investors are turning from high-priced shares.
The balance of shares sold short turned higher for the first time in three weeks, with the balance of short positions standing at 791.93 billion yen, up 4.27 billion yen.
The long-short ratio fell to 2.00 from the preceding week's 2.01 in terms of value but declined to 2.84 from 2.87 in volume.
The Nikkei average ended Friday, the last trading day for fiscal 2000, at 12,999.70, down 214.84 points, or 1.6 percent, from a week earlier.
The key market gauge suffered its biggest year-to-date drop of 693.15 points on Thursday as much of the uptrend earlier this week ran out of steam.