TOKYO — You don't mess with 1,500 years of tradition and a link to the Sun Goddess without provoking a fight, so perhaps it should be no surprise that a backlash has materialized against Prime Minister Junichiro Koizumi's plan to allow women to ascend to Japan's imperial throne.
But the gathering tempest over what seemed to be just another of Koizumi's modernizing steps is a measure of how his iron grip on Japanese politics has weakened in recent weeks.
Regarded as virtually unassailable after his crushing electoral win in September, the prime minister has seen opponents come back to attack on several fronts, from his handling of the imperial succession changes to his ties to fraud suspect Takafumi Horie.
Tuesday's announcement of an unexpected pregnancy that might produce another male heir in an imperial family that was running out of them has further rallied opponents of Koizumi's rush to change the male-only succession law.
The pregnancy of Princess Kiko, 39, wife of the second-in-line to the throne, removed the sense of urgency Koizumi was counting on to institute the change before he leaves office in September.
Koizumi vowed to press ahead with a new succession law, but the news was just the latest blow to knock him off stride. Re-energized critics have questioned the durability of the prime minister's agenda for economic reform and the fate of a foreign policy defined by coziness with Washington and frosty relations with neighbors China and South Korea.
Such a rebellion against the Koizumi brand of politics seemed unthinkable a month ago. His landslide win had left opponents discredited as "forces of resistance" and mostly cowed into silence. Koizumi's place in history as one of Japan's most powerful postwar leaders was already being written and he was preparing to anoint a successor who would continue dismantling the old power structure.
"Koizumi's great ambition was to surpass his predecessors and become the 'super kingmaker,' and until recently I thought he would succeed," Takashi Tachibana, a leading commentator, said of the prime minister's ambition to remake Japanese politics. "But the tide has changed. Now there are many voices of opposition, and his chance to be a super kingmaker is gone."
The kryptonite in this case may have been the arrest of Horie, the brash symbol of go-go capitalism and head of Internet portal Livedoor Co. who ran as a candidate for parliament in the last election under Koizumi's reform banner.
Horie was hardly a political sophisticate, and had previously been thought of more as a party animal than a party man. But to Koizumi, he was a walking billboard for the youthful anti-establishment mood the prime minister's reelection campaign was trying to create.
Now Horie sits in a police detention center, being grilled by prosecutors who suspect Livedoor was built on financial fraud. Media that once touted his lifestyle excesses with celebrities and his "greed is good" speeches now wag fingers at him. Images of a sweaty Horie dancing with fellow executives at a party in December have run back-to-back on television alongside campaign outtakes of him standing beside members of the prime minister's inner guard, including Heizo Takenaka, the architect of Koizumi's push for smaller government and market liberalization.
The prime minister's embarrassment has provided badly needed oxygen for the old guard, giving them the political legitimacy to strike back.
Significantly, many of those opposed to Koizumi's reforms are also those most inclined to seek better relations with China. They have been alarmed by the damage done to Japan's standing in Asia by Koizumi's visits to Yasukuni Shrine, which commemorates Japan's more than 2 million war dead -- including the war criminals deemed responsible for launching the invasions across Asia that led to disastrous defeat.
And they worry that Koizumi seems to be paving the way to be succeeded by Shinzo Abe, an outspoken defender of visits to Yasukuni.
Many observers see the recent political upheaval, from the Horie affair to the fracas over the imperial succession, as signs of a struggle within the country's political, business and media establishments over Koizumi's successor -- and by extension, the future of Japanese policy toward China.
"The Japanese mass media have exaggerated the Livedoor scandal, but it's just gossip," said Naoki Murakami, senior economist at Goldman Sachs in Tokyo, who argued there is a consensus in economic circles on the need to continue with reforms. "The real point is: Who will be the next prime minister?"
In that struggle, Koizumi has cultivated some powerful enemies, among them Tsuneo Watanabe, the influential publisher of the conservative Yomiuri media empire.