With less than a 0.1 percent share of Japan’s car market, Alfa Romeo knew it couldn’t match the marketing muscle of the local giants like Toyota Motor Corp., which together make nine out of every 10 vehicles sold in the country.

So Tiziana Alamprese, marketing director in Japan for the Italian car brand, aimed her efforts at a group of customers usually overlooked by most domestic companies: gay men and lesbians. The maker of the 4C sports car, owned by Italy’s Fiat SpA, tied up with local gay organizations and began sponsoring gay film festivals and pride events, where it hands out red Alfa Romeo condoms.

“Alfa Romeo is a sexy brand,” said Alamprese, who began the campaign in 2011. “When you buy an Alfa Romeo, you make a strong statement. It’s about your identity, being yourself, making an individual choice, and we wanted to work for a cause that matches that brand value.”

While major U.S. and European companies have targeted gay consumers since at least the 1990s, the trend has been slow to catch on in Japan, where same-sex relationships still lack legal recognition and are rarely discussed in public.

With opinion polls showing a growing acceptance of homosexuality, that is beginning to change as companies from SoftBank Corp. to Dentsu Inc. make forays into gay-oriented marketing.

Luring the companies is a market of ¥6.6 trillion in annual consumer spending, according to Qocci, a Tokyo-based consulting company that has advised SoftBank and West Japan Railway Co.’s hotel business on targeting gay customers.

“They know that there’s a market,” Masaki Higashida, a former Deutsche Bank AG analyst who founded Qocci in 2007, said in an interview. “The majority of gay people can’t get married or have kids, leaving them with more discretionary income.”

SoftBank and Alfa Romeo were among the sponsors last year of the Tokyo International Lesbian & Gay Film Festival and the Tokyo SuperStar Awards, a gala to recognize contributions to the lesbian, gay, bisexual and transgender, or LGBT, community.

Other sponsors of the awards included Google Inc., Dentsu Inc., IBM Corp., Ernst & Young LLP, Deutsche Bank and Bloomberg LP, the parent of Bloomberg News.

“We believe LGBT people should be appreciated as individuals, and that’s why we decided to be a sponsor,” said Nori Kobayashi, a spokeswoman for Dentsu.

The Tokyo-based advertising agency advises clients to reach out to gay men and lesbians both in terms of marketing and their working environment, Kobayashi said.

Mariko Osada, a spokeswoman for SoftBank, declined to discuss details of the mobile carrier’s gay-marketing efforts.

“We do sponsor small events like the LGBT film festivals, but the company doesn’t have any specific attachment to the cause,” Osada said.

U.S. and European companies have long targeted gay men and lesbians.

Ikea Group, American Express Co., Apple Inc. and American Airlines used gay-themed advertisements as early as the mid-1990s.

Japanese companies have also hired consultants to target gay audiences overseas. Out Now Global, a U.S.-based gay-marketing agency, lists Toyota and Sony Corp. among clients on its website.

Attitudes toward homosexuality have been slower to change in Japan than in the West, said Jeff Kingston, director of Asian studies at Temple University in Tokyo.

About 5 percent of the country’s 127 million people identify themselves as gay, lesbian or transgender, according to a 2012 market survey by Dentsu.

“There’s still a strong patriarchal foundation to the Japanese family, and ideas about proper gender roles remain very strong,” Kingston said in an interview. “In some societies, these barriers are eroding more quickly. In Japan, not so.”

Still, a global poll released in June by the Pew Research Center showed that acceptance of homosexuality in Japan and other parts of Asia is growing.

The proportion of Japanese who said gay men and lesbians should be accepted by society grew to 54 percent in 2013 from 49 percent in 2007, according to the survey.

By comparison, 60 percent favored acceptance in the U.S., up from 49 percent six years earlier.

More than eight in 10 young Japanese, or 83 percent of respondents between the ages of 18 and 29, supported accepting gay men and lesbians, according to the poll.

Other signs of greater openness are also emerging. In March, Tokyo Disney Resort hosted its first same-sex wedding, when two lesbians in white gowns exchanged vows at the theme park and posed for photos with Mickey and Minnie Mouse. The ceremony was symbolic only, as Japan doesn’t legally recognize same-sex marriages.

That same month, Tokyo kicked off its first weeklong gay-pride celebration, Tokyo Rainbow Week, with sponsors including Alfa Romeo, Dentsu, IBM and Google.

And in a landmark ruling last month, the Supreme Court recognized a transgender man as the legal father of a child born to his wife through in vitro fertilization using sperm from a third person.

“Compared with when I came out of the closet, which was when I was 17, society has changed a lot,” said Wataru Ishizaka, a 37-year-old member of the Nakano Ward Assembly in Tokyo. “I think acceptance is definitely gaining.”

Kingston of Temple University estimates it may take Japan another 20 years to enact significant gay rights legislation. Although younger Japanese are more accepting than their parents, the country is run by a “conservative political elite,” he said.

At Alfa Romeo’s Japanese unit, Alamprese’s gay-marketing proposals initially ran into resistance from local managers, she said.

In 2012, the year after the campaign began, Alfa Romeo’s sales in Japan more than doubled to 4,452 vehicles from 1,863 the year before, according to figures from the Japan Automobile Importers Association. Last year, deliveries fell to 3,148 as Alfa Romeo introduced only one new model in Japan, compared with two in 2012.

The marketing campaign hasn’t sparked any backlash, said Alamprese, who predicts that more companies will follow suit, especially in areas such as fashion and cosmetics.

“There are so many possibilities,” Alamprese said. “We’re talking about lots of money.”