Train stations are surrounded by "pink salons" promising sexual massage and "telephone clubs" where men line up liaisons with teenage girls.
Convenience stores stock brothel guides as thick as telephone books. Household mailboxes are stuffed with unsolicited "delivery health" ads emblazoned with color photos of lusty schoolgirls tearing off their plaid skirts.
Surveys by anti-prostitution groups suggest that up to 40 percent of Japanese men have paid for sex at least once. But last year there were only 1,032 arrests.
Most of those were pimps, because Japan's anti-prostitution law targets sex brokers, not the prostitutes or customers themselves, said Takeshi Koyanagi, deputy director of the Justice Ministry's research department.
"It's very hard to prosecute," Koyanagi said.
Soaplands duck the law by billing themselves as assisted bath houses. The tacit understanding is whatever else happens inside is a matter between consenting adults.
When Rika has enough "good days," she pockets Japanese Yen 1 million (US$8,200) a month. That's way better than her old job waiting tables, which she describes as "too tough."
"It's a move up," says Rika. "I want to save for the future, but I also like shopping."
A little more than a hundred years ago, Rika would have been, like her predecessors in the "Nightless City," a prisoner displayed behind barred windows, with little hope of buying freedom or a life beyond Yoshiwara's imposing moats.
Today, the moats are paved over and Yoshiwara isn't even marked on most city maps.
Well-heeled customers are dropped off by hired cars and treated to complementary whiskey drinks and cigarettes in velvet-lined lounges. The workers get a week off every month and regular health checkups, not to mention enough cash for those regular trips to Tokyo's glitzy Ginza shopping district.
A two-hour visit to Rika's costs Japanese Yen 45,000 (US$369), modest by soapland standards. Rika takes home half.
That's good pay, but soaplands -- even in bastions like Yoshiwara -- are vanishing like the geisha.
Nothing symbolizes Yoshiwara's seedy flip side more than Tokyo's Kabukicho district, where women like Hitomi prowl the frenetic, neon-bathed alleys.
Prostitution has always exposed women to disease, violence and extortion. But activists say Japan's bad economy makes women more willing to risk low-end work.
Women at soaplands are protected by burly, tuxedo-clad bouncers ready to pounce whenever workers press a panic button installed in each room. But on the street or in a gangster-run massage parlor, there are no such safeguards.
Conditions are especially bad for the estimated 12,000 foreign sex workers like Hitomi, said Yayori Matsui, director of the Tokyo-based Asia-Japan Women's Resource Center.
Many of them were trafficked into the country and indentured by debt. The economic slump means it takes them nearly twice as long, up to a year, to buy back their freedom.
Matsui says it's an uphill battle, in part, because of changing mores.
"There is also a growing point of view that it is a woman's right to engage in prostitution," she says. "I feel helpless against this trend."
Like many foreign workers, Hitomi was lured to Japan with the promise of a job -- in her case, a real job inspecting rubber sealants for refrigerator doors.