The eldest member of six-member idol unit Especia was born in 1989, so when I ask them about life during Japan’s early ’90s bubble era they can only imagine what it was like.

“I picture people throwing a lot of money around,” says Haruka Tominaga, the group’s 20-year-old leader.

“My image is someone taking a taxi and paying with a ¥10,000 note without taking the change,” says 18-year-old Monari Wakita.

“Suits with big shoulder pads,” Tominaga adds. “And everyone goes to discos on the weekend.”

Despite not having experienced the decadence first hand, the Osaka-based unit’s debut album, “Gusto,” is steeped in bubble-era largesse.

Especia’s sound takes its cue from disco and the resort-ready Japanese genre called city pop. Its image is much the same, but with a lot more references to Internet subgenres that also favor early ’90s nostalgia. In the idol world, it’s this approach that sets Especia apart from the usual (and ever-increasing) fare, avoiding traditional marketing strategies in favor of, at-times, strange giveaways.

Especia started off like most of these traditional groups, though. Its six members — Tominaga, Wakita, Chika Sannomiya, Akane Sugimoto, Chihiro Mise and Erika Mori — either auditioned for the group or were moved there from other Tsubasa Records trainee projects. The name “Especia” was manager Hiromitsu Shimizu’s idea.

“I studied Spanish in college,” Shimizu says. “One day, I was using my favorite hair wax, ‘Spice’ and I thought the translation, ‘especia,’ sounded good.”

What ultimately got the group attention from idol fans, however, was Shimizu’s decision to bring Yuki Yokoyama on board as Especia’s primary producer. Yokoyama, working under the name Schtein&Longer, has made songs for so-called anti-idols BiS, and one of them, “Elegant Monster,” caught Shimizu’s attention.

“With BiS, I had brought some of my personal taste to their songs, but with Especia I can make them more prominent,” Yokoyama says.

Whereas a lot of contemporary idol-pop veers toward an uptempo that borders on hyperventalating speed, Especia’s songs unfold at a slower, relaxed pace. Yokoyama’s approach, one that he shares with the handful of outside producers who have contributed tracks to the group over a handful of EPs and mini-albums, has involved lots of ’80s pop elements: a flurry of synths, tight bass lines and a lot of saxophone — all fixtures of city pop, which Yokoyama has been a fan of for a long time.

“When I was little, I loved resorts and seeing the city at night,” he says. “Those images stuck with me, and I have tried to re-create that vibe.”

“Gusto” expands even further on Especia’s style, adding in more retro-leaning sounds across its 16 tracks.

“There are more rap elements,” Wakita says. Mise points out that this is the first time the group tried writing lyrics. The disco bounce of “Midnight Confusion” is accompanied by songs built around horns, such as “Foolish” and “Behind You.” The effect is reminiscent of something you’d hear out of early ’90s acid-jazz , such as The Brand New Heavies or Jamiroquai.

“Our target audience at first were people who wanted to feel some nostalgia for those times,” says Wakita, who happens to be wearing an old Michael Jordan basketball jersey during the interview. “But we attracted a varied crowd. This is all a new vibe for younger people.”

The strangest sonic influence on “Gusto,” though, comes courtesy of an Internet subgenre of electronic music called vaporwave. The sound developed from U.S. artists playing around with Muzak recordings — basically, if it sounded good in an elevator, it was a success. Vaporwave artists from overseas also tend to make a lot of references to Japanese consumer culture and sample older musicians such as Tatsuro Yamashita and Toshiki Kadomatsu. Tracks are then pitch-shifted down into weird, blunted-sounding creations. Yokoyama stumbled across the genre online and started making his own vaporwave tracks, though on “Gusto” these moments are only really heard in the song interludes, “I was more interested in expressing the feeling of original city pop.”

The group, though, have run with the aesthetic. At a concert at Daikanyama Unit in Tokyo’s Shibuya Ward earlier this year, an emcee introduced them as “Japanese vaporwave idols.” Outdated technology — once the cutting-edge, but now a punchline — is a key visual aesthetic in vaporwave and Especia’s music videos. Cheesy visual effects define “No1 Sweeper” while their most recent clip for the sweet “Kurukana” plays out as a “world weather report” featuring what look like Windows 95 screensavers. Yokoyama has gotten in on the trend, too, as he has redone several Especia songs in the style of supermarket background music, available on his SoundCloud page.

“Vaporwave samples a lot of Muzak, but what you hear at grocery stores is usually Muzak versions of pop. So I was imagining Especia as being mainstream enough to be played in supermarkets.”

All of this is done to make Especia different from the idol masses, and it extends to packaging and merchandise.

“The CD cover of ‘Gusto’ doesn’t feature any of us,” Mise says. “Idols are usually always on the front, but our picture is on the back.”

This has been a consistent strategy in the way Especia is marketed, with T-shirts even going so far as to not mention the group’s name and instead feature fictional corporations that dabble in things like food-delivery services. It’s this approach that helps make the unit one of the best “alternative idol” acts in Japan right now, but “Gusto” is a solid album on its own and rarely lags. It lasts as long as most idol-pop CDs (more than an hour), but other groups tend to burn up their sugar-fueled tunes early on. Yokoyama’s varied approach makes the album enjoyable throughout.

Especia still indulges in one kind of idol marketing strategy, though. If fans buy both versions of “Gusto,” they can get a limited-edition copy of a live performance from late last year. The twist? It’s a VHS tape!

“I used to record things on those all the time,” Mise says before Wakita spends some time fondly recalling video stores. Mori, meanwhile, appears a little lost.

“I was aware they existed . . . but I don’t think I ever watched one.”

“Gusto” is in stores now. Especia plays Daikanyama Unit with tofubeats on June 6 (11:30 p.m. start; ¥2,500 in adv.; 03-5459-8630); Daikanyama Loop on June 7 (6 p.m. start; ¥3,100 in adv.; 03-6277-5032). For more information, visit www.especia.me.