In a rare development in recent months, the daily turnover on the Tokyo Stock Exchange's first section topped 1 trillion yen on May 17 and stayed above this level on four of five trading days last week.
Riding high on the growing wave of buying, Tokyo share prices then surged along a broad front.
Foreign investors vied for leadership once again, buying 322.3 billion yen more than they sold in the third week of this month alone. They have remained net buyers for the past five weeks.
Investors took heart from a string of upbeat economic and corporate earnings reports.
In a monthly report for May, the government declared earlier this month that the economy is bottoming out.
Many listed firms are now forecasting a V-shaped recovery in profits for the current business year. An interim tabulation of earnings forecasts shows a 64 percent year-on-year rise in pretax profits for the year to next March.
Although Wednesday's government report shows a slower-than-expected rise in industrial production in April, the report offers fresh evidence of improved activity in the manufacturing industries.
While the March rally was fueled largely by tightened controls on short selling, the market is now counting on an improved picture of economic fundamentals.
The 225-issue Nikkei average appears likely to test 13,000 in the near term.