Lightning Rod.(Japan's foreign minister Makiko Tanaka)

Before she took the helm as Japan's top diplomat last April, Makiko Tanaka told NEWSWEEK that she hoped to be her government's "brains" on foreign policy. Half a year and several less-measured words later, Japan's first female foreign minister has become something quite different to maverick Prime Minister Junichiro Koizumi--his Achilles heel.

In recent weeks Tanaka's long-simmering dispute with career Foreign Ministry bureaucrats has flamed into open warfare, undermining not only her prospects at the ministry but her boss's ambitious reform agenda. She has failed in a bid to dismiss key ministry personnel, accused an aide of stealing one of her rings and quarreled with a ministry colleague over who would attend an imperial garden party. Last week, in a virtual no-confidence vote, the Diet rejected Tanaka's request to attend this week's United Nations General Assembly meeting in New York. "They're digging holes and placing land mines in front of me," the 57- year-old foreign minister told her hometown supporters recently. If she doesn't tread more carefully, the real casualty may be Koizumi, who can ill afford to hand his old-guard opponents such a high-profile issue.

The struggle between Tanaka and her underlings has little to do with diplomacy. Her performance on the world stage has been tentative but harmless. The real issue is her heavy-handed attempts to reform a corrupt ministry run by a powerful old boys' network. Entrenched bureaucrats have blocked her moves to transfer senior staffers and nominate ambassadors. To sabotage further reforms, diplomats inside the normally tight-lipped ministry leaked anecdotes accusing Tanaka of being prone to temper tantrums and panic attacks. In one case, they alleged that she had released top-secret information pertaining to the location of senior U.S. officials following the September 11 terrorist attacks in New York and Washington. The badmouthing "has verged on harassment and intimidation," says Takashi Inoguchi, a political scientist at Tokyo University.

Tanaka's tribulations are part and parcel of the larger battle that the pro-reform prime minister is waging. Tanaka and Koizumi share similar pedigrees: both are outspoken Liberal Democratic Party renegades with long records of criticizing the party's status quo center. Swept to power in a grass-roots backlash against the LDP mainstream in April, they remain hugely popular with Japanese voters. Yet translating "people power" to political muscle has proved difficult for both. Tanaka's shrill broadsides against the bureaucracy, combined with her lack of foreign-policy expertise, have "confused the issue of trying to get control over the bureaucracy with simply being nasty," says Columbia University's Japan watcher Gerald Curtis. "Unfortunately she's given her enemies lots of ammunition to attack her with."

Struggles between politicians and bureaucrats have shaped Japanese governments for centuries. Samurai sometimes detained local lords to prevent them from "meddling" in state affairs. After the Meiji Restoration, noblemen led by Baron Aritomo Yamagata undermined elections with a law that barred politicians from making personnel appointments in ministries. The rules turned government into a collection of rogue power centers that followed self-serving agendas. In postwar Japan, democracy has served as a fig leaf to mask a similar system. Bureaucrats loyal to the ruling LDP control key ministries, while political appointees are mere figureheads.

Like Koizumi, Tanaka entered office with the goal of cleaning house. Initially the ministry looked like a fat, scandal-ravaged ...