Japan's biggest fleshpot, Kabukicho, squats over a sprawling kilometre-long block of central Tokyo, a gaudy patchwork of sex clubs, massage parlours and love hotels just two minutes' walk from the world's busiest train station, writes David McNeill

On a Friday night the streets teem with the flotsam of a wired city winding its way down into the weekend: drunken salarymen hunting for cut-price kicks mingle with hawkers, hoodlums, curious high-school students and perhaps more unlikely thrill-seekers: wealthy middle-aged women.

Some of the women are headed for a club called Ai, or Love, where Seiji Naruto can be found working as a "male host". A lank-haired, lantern-jawed 30-year-old wrapped in a designer suit and sporting a gold-embossed business card that smells of aftershave, Naruto comes across as thoughtful and attentive, his demeanour that of a practised listener.

Among the staff he is known as No 4, his current ranking in the club's league table of earners for the month. "I'd like to be No 1, but I've got a long way to go," he says. "It is tough learning what women want."

Outside the club, and on a nearby billboard, Naruto's neon-lit face smiles down at curious women, three photographs down from a large mugshot of the top host, who frankly is not half as good-looking, although he shows off more chest. "Face is only part of this game," Naruto explains.

In Ireland Naruto would be called a gigolo, but in Japan he is just one of an estimated 12,000 male entertainers - nearly half of them in Kabukicho - working in a perfectly legal industry that Forbes magazine estimates is worth more than €1 billion a year. His job is to lavish attention on his female clients and persuade them to relax, laugh and spend money on the club's outrageously priced drinks. Often that means forming relationships with women outside the club. "I don't mind the term gigolo, because after all we live off women," he says. "But this job is not as easy as it looks. You have to learn how to read people, to make them feel good."

Just two or three hosts in 100 last more than a few months. Of those who survive, most will earn an average of €8,000 a month for their clubs, and although Naruto is way beyond that he is still far behind No 1, who is hitting somewhere from €80,000 to €120,000. Most of the hosts are in their 20s and 30s, but some are in their 60s, catering to women aged anything from 21 to 70. "Most of the women want younger guys," says Naruto. "Few older men can stick this life."

For those who do the rewards can be considerable: Naruto takes home more than a million yen (€7,250) a month.

Inside Ai the air is thick with cologne, cigarette smoke and cheesy showbiz tunes pumped out by a band in tuxedos. Men outnumber women by 10 to one. Every whim is catered for: women reaching for cigarettes are instantly, comically, surrounded by four lighter-wielding lotharios, drinks materialise seconds after they're ordered and conversation is lubricated with flattery so thick it could make the fake flowers wilt.

The attention does not come cheap: most of these women will leave behind the equivalent of hundreds of euro, and some will leave a lot more - a final bill for millions of yen is not unheard of in a club where champagne costs €1,800 a bottle. The money comes from a variety of sources: real-estate empires, wealthy husbands, even banks. "Some of the women borrow to come here," says 41-year-old Johnny Kugai. "Quite a few work as prostitutes and need to relax after catering to men all week." But over the past decade Japanese television has also noted with incredulity the rise of the businesswoman client with money, and sense, to burn.

What makes a good male host? Ai's owner, Takeshi Aida, who sold French beds before he tried the host business 35 years ago, says it's a combination of conversation, character and looks. "You must be able to communicate sincerity, kindness and strength of character in the eyes," Aida says, waving a chunky jewellery-encrusted hand to make his point. "Playboys are completely useless. Women can spot them a mile off. And you have to be able to dance and work hard. Forget two-week holidays."

Certainly, the top hosts are models of industrious enterprise rather than libido off the leash. Naruto works seven shifts a week, deep into the night. Exhausted hosts with ties undone and translucent vampire skin from months of heavy drinking and late nights are a common sight on early-morning trains in Tokyo. Even sleep is no refuge, because the hosts are expected to meet clients outside work, whatever the time; business cards always include a mobile-phone number. "If a woman calls and wants to go shopping or to a movie, I've got to go," says Naruto. "She pays."

Like everybody who has chosen this profession, Naruto must work a delicate professional tango with the women who adopt him, draining them of money while weaving a charm spell that masks the sound of bank accounts being sucked dry, withholding sex while constantly hinting at its possibility. "Most hosts sleep with clients, but it's not good, because you break the tension and it makes things more complicated," says Naruto. "The game is over when that happens."

Has he ever fallen in love with a client?

"Once in a while, but it's not good for business," he says. "These things should be kept separate. You have to keep a lid on your feelings."

It must be tough watching your face slip down the league table outside the club as you get older, I suggest. "I'm going to get out of this game long before that happens," he says. "Some of the guys here are in it for what they can get, but my aim is to set up my own business by the time I'm 35."

His boss believes Naruto has got what it takes to make the coveted No 1 spot. "Look at that face," he says, chunky finger jabbing the air again. "It's all in the eyes, and he has sincerity."

The club says the bulk of its customers are women who work in the entertainment business, including hostesses, prostitutes and barmaids.

But businesswomen, curious office ladies and wealthy, bored housewives are also a fixture.

I talked to three customers.

Manami is an attractive and sharp-featured twentysomething, already pretty drunk by 12.30 p.m. She says she works in mizu

shobai, or "water trade", a euphemism for anything from

bars to clubs.

"I look after oyajis" - a derogatory term for middle-aged men - "all night, and it's really tiring," she says. "I come here to get healed. My friends do too. I suppose it's a bit of a vicious circle: we heal the oyajis and the hosts heal us. One of my friends slept with a host, but it's sort of like loving a movie star. It's best to protect the perfect image in your mind. Close contact brings disappointment."

Rina came in with her friend, who didn't want to be identified. They work in the office of an insurance firm and wear jeans and T-shirts.

"I've seen the hosts on TV so wanted to have a look myself," she says. "The guys are nice until you see their skin close up, which is sometimes bad, but it's fun to be pampered. There's no way I'm going to get carried away, though. I have to get up for work in the morning."

Kyoko is a prosperous-looking woman in her late 30s who laughs a lot and chain-smokes Marlboro Lights. She says she runs a restaurant nearby and that she is married but that her husband

goes away on a lot of business

trips.

"I don't think he knows I come here, or at least he doesn't care," she says. "We are married in name only."

She first came to the club out of curiosity but liked the men. "They're gorgeous and sweet. I know they're only after money, but that's OK. We all have to make a living."

When I ask if she would sleep with a host she laughs and says: "They'd have to pay me!"