Shinzo Abe is president of the Liberal Democratic Party and was elected prime minister of Japan in December 2012. He also served as prime minister in 2006 after being elected by a special session of Japan’s National Diet, but resigned after less than a year.
Worry over hawkish Shinzo Abe's nationalist agenda
Poll victory could allow prime minister to switch his focus to loosening commitment to pacifism
Japanese Prime Minister Shinzo Abe's decisive victory in an election on Sunday was so big there are suspicions he will lose interest in difficult economic reforms and pursue his nationalist agenda instead.
The victory gives Abe a stronger mandate for his prescription for reviving the stagnant economy. Coincidentally, it could also give lawmakers in his own party, some of whom have little appetite for painful but vital reforms, more clout to resist change.
Video: Japan PM pledges reforms after election win
Abe repeated on Sunday he would focus on fixing the world's third-biggest economy with his "Abenomics" mix of hyper-easy monetary policy, fiscal spending and a growth strategy including reforms such as deregulation.
But some, including businesses with a big stake in the matter, worry the hawkish leader will shift to focus on the conservative agenda central to his ideology.
Despite the hefty win, the strength of Abe's mandate was diluted by low voter turnout.
Media reported the turnout was 52 per cent, 5 percentage points below the turnout in the last upper house poll in 2010. That could keep up pressure to stay focused on the economy.
In an editorial, the Nikkei business daily called on Abe to "focus all of his political capital on the success of Abenomics".
It said: "We hope this election will become a turning point for Japan to rid itself of two decades of lost economy and politics."
Abe's detractors fear Abenomics has been a Trojan Horse aimed at securing the hawkish premier enough power to implement his conservative social agenda. For now, many experts suggest, Abe is unlikely to turn his back on economic matters. "My understanding is that Abe-san has three faces: Abe as right-wing, Abe as a pragmatist, Abe as the economic reformer," said Shinichi Kitaoka, president of the International University of Japan. "He has been showing the third face so far and will try to do the same after the election."
Abe's detractors fear a loosening of Japan's constitutional commitment to pacifism, a boosting of the military and a more strident tone in already-strained relations with China and South Korea, both of whom have territorial disputes with Tokyo.
One clue to how Abe intends to proceed on the touchy topic of wartime history will be whether he visits the Yasukuni Shrine for war dead, where Japanese leaders convicted as war criminals by an Allied tribunal are also honoured, on the emotive August 15 anniversary of Japan's defeat in the second world war .
"The first Abe really wishes to go [to Yasukuni on August 15] but I guess he will refrain from that," Kitaoka said. But he added: "Mr Abe is somewhat unpredictable."
Abe moved quickly to improve ties with China and South Korea at the start of his first 2006-2007 term. But he has taken a tough stance towards Beijing in particular this time.
Concerns are simmering about the risk of an unintended clash near disputed isles in the East China Sea, where Japanese and Chinese vessels have been playing a cat-and-mouse game.
"In that environment, something could go wrong," said Michael Green, of the Washington-based Centre for Strategic and International Studies.
Additional reporting by Agence France-Presse