The first report came in July--a woman had been slapped to her knees by a man who had approached her in a telephone booth and struck up a conversation. She had tried to walk away when he began to get too intimate, but he grabbed her arm and spun her around, giving her a roundhouse, openhanded smash. She screamed and fell, and the man ran off.

"At that point, we thought we had a rapist," says Superintendent Tsunenori Tani of the Hitachinaka West Police Station in Ibaraki prefecture. "But a few days later, he tried to pick up a high school girl and tried to choke her with a rope when she refused. It had gone beyond being a case of sexual assault, it was attempted murder." The police were worried, and with good reason. The attacker struck again on September 14.

It was nearly 2am, and a 28-year-old housewife who had quarreled with her husband was striding toward a nearby phone booth. A man's voice said, "Where are you going in such a hurry?" His speech was smooth and friendly, so she unwittingly slowed her pace. But when the man offered to take her home, she balked. He pushed her into the middle of a field and began beating her. By the time he got around to tearing off her flimsy sweatsuit, her face was smeared with blood. Wadding up the sweats and throwing them at the woman's feet, the attacker fled. She lay moaning in the field, her nose broken, two front teeth missing, clad only in her bra and panties.

The officers' earlier fears had been well-founded. "This guy was eventually going to kill someone," says the superintendent. "We had to find him." So they worked out a scheme that could have come straight from Hollywood.

They had a fairly good description from the battered woman. "But even then," says Chief Tadaaki Hirayama, "when you get a random killer, like this man seemed to be, it's almost impossible to ferret him out."

"We decided to use decoys to catch him," continues the chief. "If you set out a flower, the bees will gather." Their first idea was to use female officers, but female officers are not trained to fight. "We would have had to shadow them with 25 officers for protection." The attacker seemed partial to smaller women, so the senior policemen decided that the two shortest men on the force--officers Watanabe and Abe--should pose as women. It was not a case of volunteering; the pair were ordered to do the job.

"They had just got back from riot-squad duty at the Aum headquarters in Kamikuishiki," says Tani. "Both have black belts in judo and are ranking kendoists. They didn't want to dress like girls--but we knew that they wouldn't be afraid of some guy trying to slap them around, even if he was 10cm taller." To make the two young officers pass as female, the police turned to Kyoko Fujihara, the city's premier hairdresser, for advice.

"They were such nice young men," recalls Fujihara with a laugh. "And so serious." She instructed the men on feminine movements and planned their makeup. "They were really tense at the time," says the superintendent. "Standing around in their dresses, chain-smoking."

"But they were smoking like men," gruffly interrupts the chief. "Know how a wayward young woman smokes? She squats, with her arms on her knees, the cigarette between her thumb and forefinger. They weren't doing it right, so I made them practice."

On September 22--a Friday night--the impersonators prepared to embark on their first mission. Hairdresser Fujihara took one look at Officer Abe and made him re-shave. She then did the two men's makeup, fitted them with shoulder-length wigs and lent them her daughters' clothes (more realistic than those the men had brought). At midnight, the "flowers" were ready to bloom.

Hitachinaka is a small, newly emerging city. "In towns like ours, you've got a string of buildings--then suddenly a vacant field for 50 or 100 meters," says the chief. "Nights are dark, and you can never tell what will happen."

Just after 1am, the two impersonators, each with nine watchers, took to the streets. The decoys were each assigned to a phone booth where they would squat, phones to their ears (hair hanging down over their faces) for 20 minutes--then leave the box and stroll away. Just as Officer Watanabe left his first telephone booth, a biker roared up. "Hey babe--where ya going?" he demanded. "Give ya a ride on the ass end." One of the hidden officers stepped out and flashed his ID. "Move along." The biker did, but he was only the first of many to attempt picking-up the cross-dressing policeman. Officer Abe had his problems, too. He was returning to his phone booth when an inebriated salaryman staggered up. "Whaddaya doin' out so late?" he wanted to know. Abe ignored him and walked on. The drunk tagged along, breathing alcohol fumes in his ear. Finally Abe couldn't take it anymore. He turned, grabbed the drunk by the lapel and growled, "I'm a cop. Buzz off." The drunk's eyes widened. "Ooooh. A lady officer." He examined his new discovery more closely. "Weeelllll . . . You lady officers need protection, too. Why don't you just let me see you home?"

The Hitachinaka West Police Station rocked with laughter when the officers returned. "We came up empty-handed," says superintendent Tani, "but that night we learned that the bait would work. We knew that it was only a matter of time before he struck again, so we wanted to catch him before it was too late."

The following Thursday, all dressed up and flaunting their best feminine walks, the impersonators ventured out a second time. Officer Abe headed for Taisei-cho; officer Watanabe took his team across town.

Hitachinaka nights, as the police chief says, are dark. Several blocks south of brightly lit Katsuta Station, the street-lights thin out into a scattering of fluorescent tubes atop spindly poles. Anything off the main street is plunged immediately into the shadows. On the left, the Hitachinaka Culture Center stands back from the road, dark except for the odd garden lamp. Girlish chatter and the low rumble of an adolescent male voice floats through the air. A couple sits on a bench, entwined. Across the street, by the sushi shop, a girl stands in a public phone booth, talking with her head down, hair covering her face. The street leads east into the darkness.

Officer Abe played the girl in this phone booth several times. There was little traffic on the street that night, and no one had tried to pick him up. Then just after 2am, as Abe left the booth walking east, a light-colored sedan passed and slowed. Abe kept walking, his head down, and the car picked up speed and disappeared. As soon as it was out of sight, the car pulled over.

A few minutes later, a man about 170cm tall and wearing glasses came ambling west on Abe's side of the street. He was trying to act nonchalant, but the shadowing officers could see that he was aiming directly for the girlish figure walking toward him. From their vantage point, he matched the description they had been given by the housewife who had lost her front teeth. As the man drew up to Abe and opened his mouth to speak, he was surrounded by plainclothesmen. There was no struggle, no Hollywood-style chase.

The man taken into custody was Tetsuo Hosaka, 45, a machinist by trade and a hard worker by reputation. According to chief Tani, his confession was a tale of bitterness and increasing violence. His wife had left him around the beginning of the year and since then he had become increasingly frustrated. Several times, he'd been successful at picking up women and convincing them to have sex with him. But one night, he hit a girl who had refused. Her tears made him run. But he was even rougher with the next one, choking her with a rope. Then the housewife. Luckily, remorse had saved her. According to the police, Hosaka confessed that he had torn her clothes off, ready to rape her--then saw her bloody face. "That shocked the lust right out of him," says Tani. "He ran."

"And you know what?" says chief Hirayama with a tight smile. "He still doesn't know that the girl he was about to pick up when he was caught was a man."