Morihiro Hosokawa, the former prime minister who rocked and transformed Japanese politics in the early 1990s, is back, this time as a leading candidate for Tokyo governor, running as an anti-nuclear crusader seeking the abolishment of all atomic power plants.

But questions linger about the credentials of the man who, in 1993, became a national hero when he broke the Liberal Democratic Party’s long-standing grip on power.

Now 76, Hosokawa was indeed a political superstar 20 years ago. This time around, however, he’s failed to stir excitement, despite intensive media coverage and support from popular ex-Prime Minister Junichiro Koizumi, who has joined Hosokawa’s anti-nuclear drive.

According to a poll conducted by weekly magazine Sunday Mainichi on Jan. 15, former welfare minister Yoichi Masuzoe, an independent supported by the LDP, is the most popular candidate by a wide margin.

Some 44.1 percent of 1,018 respondents support him, while 20.3 percent backed Hosokawa. Sources said unofficial polls taken by other major media have also put Masuzoe in the lead.

In the same Sunday Mainichi poll, 47.8 percent backed the abolishment of nuclear reactors, versus 22.7 percent who want to keep them.

But the anti-nuclear voters are split, with 33.3 percent supporting Hosokawa and 31.4 percent supporting Masuzoe, according to the weekly magazine.

In fact, all three of the top candidates — Masuzoe, Hosokawa and Kenji Utsunomiya, former chairman of the Japan Federation of Bar Associations — have called for the eventual elimination of nuclear power plants, apparently splitting the anti-nuclear vote.

Tokyo does not host any atomic plants and how its governor could influence the central government’s nuclear policy remains unclear at best.

That may be another reason Tokyo residents appear to be more concerned about other issues.

“It’d be incorrect to say there won’t be any impact (from Hosokawa’s joining the race). But I don’t think (the impact) is big,” said Chief Cabinet Secretary Yoshihide Suga during a news conference on Jan. 14.

When the official campaign period starts Thursday, the still popular Koizumi plans to use his powerful communication skills to stump for Hosokawa “day after day,” said an official at Hosokawa’s campaign headquarters.

A key factor is how many swing voters Koizumi can woo.

Born in 1938, Hosokawa earned the nickname “Tono-sama,” or Mr. Lord, for his aristocratic family background and easy manner.

A direct descendant of a samurai lord of Kumamoto, Hosokawa also has in his lineage a grandfather, Duke Fumimaro Konoe, who twice served as prime minister, in the 1930s and ’40s.

In his memoir, run by the Nikkei newspaper in 2010, Hosokawa recalled that he decided to become a politician in 1956, when Fumitaka Konoe, an uncle who served as a secretary to that grandfather, died in a prison in Siberia.

After graduating from Sophia University in Tokyo, Hosokawa worked as a reporter for the Asahi Shimbun to lay the groundwork for his career as a politician.

In 1983, Hosokawa was elected governor of Kumamoto, and served two terms until 1991.

The following year he formed Japan New Party, and was its only member in the beginning. But in the 1993 Lower House election, the party won 35 seats, riding a wave of voter frustration with the money-driven, corrupt politics associated with the LDP.

As a result of the 1993 election, the LDP lost its majority, paving the way for Hosokawa to become the first non-LDP prime minister in 38 years.

In 1994, Hosokawa’s eight-party coalition succeeded in enacting key reform bills changing the election system and greatly enhancing the transparency of lawmakers’ political funds.

One result was the introduction of single-seat constituencies to the Lower House, making it easier for opposition parties to take power if backed by swing voters.

Likewise, the political funds bill considerably weakened the power of LDP factional bosses, who regularly raised shady funds from various vested interests, typically with ties to the construction industry.

But otherwise, Hosokawa’s government accomplished little. He abruptly quit in April 1994, just nine months after taking office, to the disappointment of voters who had pinned their hopes on his commitment to chase money from politics.

In a memoir published in 2010, Hosokawa said he quit over deep divisions in his eight-party coalition government that had led to paralysis.

The reforms he had overseen fulfilled his political ambitions, he also wrote.

Ever since, Hosokawa has been tagged as irresponsible for so soon abandoning his administration. This reputation is likely to dog him in the gubernatorial race.

Rivals are also expected to reawaken memories of the money scandal that plagued him before he stepped down.

Hosokawa borrowed ¥100 million from scandal-tainted Sagawa Express Co. in 1982 — money that opposition lawmakers charged was a secret campaign fund that had been used in the 1983 Kumamoto gubernatorial election.

Hosokawa maintained the money was legally acquired, used to renovate his house in Kumamoto Prefecture, and was repaid over 10 years.

No facts have ever emerged to prove the suspicions of opposition lawmakers, but many still believe the loan problem was one of the factors that drove Hosokawa from office.

Since retiring from politics in 1998, Hosokawa has led a quiet life as a traditional ceramist in Yugawara, Kanagawa Prefecture.

In a recent interview by noted journalist Akira Ikegami, Hosokawa said he grew concerned about nuclear power after hearing about the contamination of the sea at the Sellafield nuclear facility in northwestern England.

Even before the Fukushima meltdowns in 2011, he was deeply concerned that the nuclear reprocessing facility in Rokkasho, Aomori Prefecture, may be vulnerable to a major earthquake, he said in the interview.

Then came the quake-tsunami disaster that knocked out the Fukushima No. 1 nuclear power plant.

“I was immediately convinced that the nuclear power plants must be stopped. I have decided to keep appealing for the abolition of nuclear plants,” Hosokawa was quoted as saying.