Tokyo's Nikkei 225 index today posted the longest winning streak in its nearly 70-year history as markets cheered the weekend election victory of Japan's pro-business prime minister.

The benchmark index rose 239 points (1.1%) to end the day at 21,697, its 15th consecutive rise and the longest since it came into existence in 1950.

The Nikkei index gained 1.4% last week, making its sixth weekly gain in a row and its longest weekly winning streak in a year, leaving investors to ponder how long it might continue.

Prime Minister's Shinzo Abe's coalition kept its two-thirds "super majority" in the lower house.

This reassured investors that his "Abenomics" economic reforms would continue, including the Bank of Japan's easy monetary policy, which has resulted in a weaker yen, benefiting exporters. 

The Nikkei's attention will now shift from to company earnings, which could underscore Japan's recovery and pave the way for more gains as long as external factors are favourable. 

Fuelled by Abe's victory and hopes of US President Trump's tax reform, the dollar rose to three-month highs above the 114-yen level, though it later fell back below it. 

The weaker yen gave many exporter shares a lift, but Toshiba shares skidded 1.2% after the company said it expects to post a net loss of 110 billon yen for the fiscal year through March, compared with its previous forecast for a net profit of 230 billion yen. 

Shares of Kobe Steel edged down 0.1%. 

On Friday, the embattled steelmaker said it had lost some customers because of widespread data falsification that had extended to its mainstream steel sheet business. 

It also admitted it had violated statutory standards set by the industry ministry.