The Nikkei index closed at a record high on June 1 after gaining on optimism about the Middle East.
The benchmark index of 225 issues on the Tokyo Stock Exchange Prime section rose 604.83 points, or 0.91 percent, to finish at 66,934.33.
The gain came from Friday's close and marked a new record for the index.
The move followed positive developments related to the Middle East, according to market reports.