As fight warms up, Koizumi's biggest foe begins to hit
Famously reluctant to take the presidency of the Democratic Party of Japan last year, Katsuya Okada is slowly overcoming another reluctance. It may be an incremental change, but the man who poses the biggest threat to Prime Minister Junichiro Koizumi in Sunday's election is learning to smile.
But as leader of the largest opposition party going into the House of Representatives election, has he left it too late to unveil a winning grin?
'When he appeared in the media, that apparent inability to smile did not go down very well with the public,' said Makoto Watanabe, a lecturer in media and communications at Hokkaido University. 'But gradually they are beginning to see it as seriousness and determination and he's looking more relaxed, smiling and slowly winning people over,'
Unfortunately for Mr Okada, he is up against an opponent who has styled himself as 'Lionheart' and, some argue, has wrapped Japan's media around his little finger.
'As a performer for the cameras, Mr Koizumi is still way ahead of him,' said Professor Watanabe. 'He has worked on his image and he knows what the media want before they know it themselves.'
That is why the cameras are focused on the prime minister as the campaign warms up and Mr Okada is frustrated the vote is boiling down to personalities over policies.
'This election is going to decide the politics and policies of the country for the next three or four years and it is very important that the people of Japan know their options,' Mr Okada said at a recent press conference at which he challenged Mr Koizumi to a one-on-one live debate on key issues.
The prime minister refused to pick up the gauntlet; on this occasion the opposition leader could be forgiven for his scowl of displeasure.
Born in the central prefecture of Mie in 1953, Mr Okada dreamed of travelling the world as a trading-company employee, but after graduating from the law department of the prestigious Tokyo University, he joined the Ministry of Trade and Industry.
In university, he says, he preferred reading to studying, with Fyodor Dostoyevsky's The Brothers Karamazov his favourite book.
He was sent to Harvard University for a year, and in the United States he developed an interest in politics. His first election victory in 1990 was as a member of the Liberal Democratic Party.
Within three years, however, he says he had become disillusioned with what he called the corruption and money politics that dominated the party and its failure to get to grips with reforms.
In 1993, he left to join the Japan Renewal Party, which evolved into the New Frontier Party. He has pledged to strive for a genuine two-party system and eradicate the influence of special interests.
A founding member of the Democratic Party of Japan in 1998, he was unexpectedly thrust into the presidency in May last year after the resignation of Naoto Kan over irregularities in his payments to the pension system.
'The party needed a clean image and he was definitely the man for that, even though he had to be talked into accepting the position,' a party insider said. He fits the bill: a father of two who lists among his hobbies black-and-white films and collecting frog ornaments, because they are considered lucky,
His party holds 177 of the 480 seats in the lower house. The LDP-New Komeito coalition holds 246, with the remainder scattered among the minor parties and independents.
Inside the final week of the campaign, public opinion surveys show the DPJ lagging behind the LDP.
Mr Okada has vowed to step down if he fails to secure victory on Sunday. But if he does pull it off, the Japanese public might just get to see a genuine ear-to-ear grin.