LOS ANGELES — Looking to capture young, tech-savvy Asian-Americans, a Long Beach, Calif., advertising agency turned East for inspiration.

The firm, InterTrend Communications, came up with a Web series that blended elements of South Korean soap operas with a novel Japanese storytelling device that employed online social networks. The series, sponsored by AT&T Inc., quickly notched nearly 10 million views on YouTube and generated 4,700 suggestions from fans about how the story should unfold.

The unusual interactive nature of the Web series, called “Away We Happened,” could provide a template for advertising in the future. It also reached beyond the intended target audience, demonstrating the growing appeal of Asian culture.

“The subculture is actually becoming the mass culture,” Julia Huang, InterTrend's founder and chief executive. “The people who are watching these Web series … are actually leading the way of how media is consumed and how the culture is shaped.”

For decades, firms such as InterTrend have worked to craft niche messages for ethnic media outlets — Asian TV channels and newspapers and magazines in Mandarin, Japanese, Taiwanese and Vietnamese.

But during the past 18 months, major corporations have become increasingly interested in wooing young Asian-Americans — many of them born in the U.S. — who are fluent in English. Advertisers recognize the size and the power of the largely untapped market of more than 18 million Asian-Americans. They are affluent, well-educated and represent the fastest-growing racial group in the U.S., according to Pew Research Center.

But tapping this audience can be tricky.

Asian-Americans watch 100 hours of TV a month, which is half the time African-Americans spend watching TV and two-thirds the hours white Americans spend in front of the tube, according to ratings firm Nielsen. But they spend twice as much as time watching Web videos as other ethnic groups, Nielsen found, and are more likely to watch videos on mobile devices.

AT&T asked InterTrend to come up with a campaign to engage young Asian Americans who often provide advice about devices and services to their parents and grandparents, many of whom are immigrants.

“In these households, the Asian youth are the tech support, and they do influence buying decisions,” said Laura Hernandez, executive director of marketing management for AT&T. “We knew that we had to use social media to reach them.”

Executives at InterTrend were intrigued by a storytelling approach that has become popular in Japan. There, Twitter users collectively write short stories that unfold in real time on the social media platform.

But InterTrend executives didn't want to confine the AT&T project to 140-character messages on Twitter, so they adapted the concept into an interactive scripted Web series enabling viewers to propose plot points on Facebook and YouTube. The firm recruited Wong Fu Productions, a short-film company based in Pasadena, to produce the series, in part, because it already had its own channel on YouTube that boasts 1.2 million subscribers.

At first, Wong Fu's founders were hesitant to because they knew that inviting the audience to help craft the script would turn into a mad dash to meet the weekly production deadlines. But they couldn't resist the high-profile challenge.

“It was an amazing interaction,” said Phil Wang, one of the three founders.

By August, the series that launched in the spring had attracted more than 313,000 people who voted and commented. The Web show, which revolved around a star-crossed couple brought together by technology, starred Victor Kim, a Korean-American break dancer from Sacramento, Calif., and an Internet personality known as Jen Frmheadtotoe, whose beauty advice has attracted 38 million views on YouTube.

“We had seen this cottage industry pop up on YouTube — this creative outlet for Asians and other minorities,” Hernandez said. “But to see it come alive, and see consumers engaged in such an emotional way, was extraordinary.”

Unlike television, the Web has become a flourishing creative outlet. Many of the top bloggers and celebrities on YouTube are Asian, whereas on television Asians in leading roles are scarce. That may partly explain the vast reach of “Away We Happened.”

“Suddenly, young Asian-Americans are becoming influencers,” said Nita Song, president of the Asian American Advertising Federation.

Two years ago, InterTrend — which also represents Toyota Motor Corp., Walt Disney Co. and insurer State Farm — enlisted a Japanese pop diva named Hatsune Miku, a popular Japanese 3-D singing hologram, to boost interest in the Toyota Corolla among young consumers. It also developed a series for Toyota featuring South Korean soap opera star Lee Min-ho driving a Camry — illustrating how a fusion of Asian cultures is helping to attract a broader audience.

“Twenty years ago, it would have been unheard of to have a Japanese brand (like Toyota) use a Korean soap opera star,” Huang said. “Back then, Chinese campaigns had to be different than Korean campaigns and different than the Japanese campaigns. But the world has changed.”