Mr Hatoyama had wanted "a horizontal society bound by human ties"
Yukio Hatoyama, who resigned as Japan's prime minister in June 2010, was brought down by political funding scandals and his failure to fulfil an election pledge over US bases in the country.
When he came to office in 2009 he was, at first glance, not unlike the man he ousted.
Both he and his predecessor Taro Aso come from the political and industrial elite.
Both had a prime minister for a grandfather.
Mr Hatoyama's family founded tyre giant Bridgestone, Mr Aso's owned a leading mining company.
Both men graduated from an elite university and spent time studying in the US, before joining the ruling Liberal Democratic Party (LDP).
But there their paths diverged. While Mr Aso climbed the LDP ranks, Mr Hatoyama left to form a new party.
Just a year after Mr Aso became prime minister, he suffered a convincing election defeat at the hands of Mr Hatoyama and his Democratic Party of Japan (DPJ) - only the second time the LDP had been beaten since World War II, leaving the quiet, unassuming Mr Hatoyama at the reins of the world's second biggest economy.
Largely unknown outside Japan, he was nicknamed the "alien" by his fellow party members, because of his somewhat quirky appearance and his reputation for being rather bland and inexpressive.
Miyuki Hatoyama claims to have been on an alien spaceship to Venus
In fact much of the attention in the wake of the election victory focused on Mr Hatoyama's wife rather than the new prime minister himself.
Miyuki Hatoyama, a former actress, claims she once visited Venus in an extraterrestrial adventure and met Tom Cruise in a past life.
Mr Hatoyama and his wife have one son, an engineering scholar living in Russia.
Yukio Hatoyama walked away from the LDP in 1993.
With a small group of lawmakers, he founded New Party Sakigake. The party was part of a reformist coalition that ousted the LDP in elections later that year.
Mr Hatoyama served as deputy chief cabinet secretary under Prime Minister Morihiro Hosokawa - but a funding scandal felled the government only eight months later and the LDP was soon back in power.
Mr Hatoyama went on to co-found the Democratic Party of Japan. Initially a minor party, it merged with three others in 1998 and steadily increased in popularity.
In 2002 he was forced to stand down as DPJ leader following strong criticism of his plan for a merger with more opposition groups.
But he returned seven years later after the resignation of leader Ichiro Ozawa in another funding scandal.
By then the DPJ was in a position of strength. It had rebounded after a drubbing in the 2005 polls, mostly because of a succession of LDP gaffes, policy mix-ups and prime ministerial resignations.
In July 2007 voters used upper house polls to show their displeasure with the LDP, awarding control of the house to the DPJ for the first time.
Voters continued to desert the LDP as the economy faltered in late 2008 and into 2009.
In his manifesto ahead of the August general election, Mr Hatoyama said he wanted to wrest control from the hands of Japan's powerful bureaucrats.
The Futenma base is deeply unpopular with many Okinawans
"I want to create a horizontal society bound by human ties, not a vertically-connected society of vested interests," he wrote.
Mr Hatoyama also said he wanted to raise spending on healthcare, child support and subsidies for farmers.
But he ruled out raising taxes to do this - prompting critics to ask where the money would come from.
A key part of Mr Hatoyama's election campaign was a promise to reassess agreements with Washington over the Futenma US military base on the southern island of Okinawa.
The island is home to tens of thousands of US troops. Residents angered by the high foreign military presence and incidents involving US forces - including the 1995 rape of a 12-year-old Japanese girl - have staged large protests against the base.
Mr Hatoyama had said he was in favour of moving the base from the island completely but in May 2010, was forced to admit that was not a feasible option and that instead, troops would be moved to a less populated part of the island.
The move prompted an angry reaction from Okinawans and had immediate political repercussions for Mr Hatoyama. He fired a coalition partner from the cabinet after she said she could not back his decision - her party, the Social Democrats, then pulled out of the coalition entirely.
Pressure built on Mr Hatoyama to stand down, not least from his own party, who feared a resounding defeat at mid-term elections to the upper house in July if he stayed at the top.
He announced his resignation on 2 June, apologising to DPJ lawmakers for "causing enormous trouble" and saying his government had "not reflected the public's wishes".