Japan's main stock benchmark breached the 40,000-point level for the first time on Monday as technology shares jumped.
The Nikkei share average was last up 0.7% at 40192.48.
Japanese stocks continue to soar to new peaks after last month shattering the life-time high set during the halcyon days of the bubble economy over three decades ago, spurred by corporate governance reform and cheap valuations.
On Monday, Japan's technology shares helped pull the Nikkei above the 40,000-point level, boosted by the ongoing artificial intelligence rally in U.S. stocks, which once again pushed the S&P 500 and Nasdaq to record highs overnight on Friday.
The broader Topix was down 0.02% at 2709.07.