It’s a week until Necronomidol’s big show and, practicing at a dance studio in Tokyo’s Shinjuku Ward, the four members make a decision to change one line from “We’ve come to bring about the Apocalypse” to “We’ve come to enact Armageddon.” Manager Ricky Wilson agrees; another problem solved.

The four-member Necronomidol claims to be Japan’s first occult-infused idol unit, and its members are still tweaking lyrics and stumbling through the choreography for their new song, “Skulls in the Stars,” but 31-year old Wilson is calm. He supplies the concept — in this case, a tale of cosmic horror set to horror disco — and the members make it their own. Besides, even if they stumble on stage, imperfection is a selling point in the idol world.

At times like this it pays to be the underdog. The unit’s low visibility allows it the freedom to experiment — and possibly fail — in ways that established acts could never risk. Necronomidol and other self-produced underground idol groups share more in common with DIY punk than polished pop — and they’re the place to be if you like your music raw.

“Saying ‘I like idols’ is the new anarchy patch. It means living on the fringe,” Wilson explains. “Once upon a time punk shows offered variance. You knew the concert that night would be different than the one last week, but the scene’s grown stagnant. It’s always the same crowd, the same performance, and that’s not fun. So people migrated to idols.”

Wilson has the chops — and muttonchops — to back his claim. Raised on B-grade horror and heavy metal in his native Pittsburgh, nine years ago he did what all college graduates obsessed with kaijū movie monsters do and moved to Japan. These days he keeps his fists and elbows on the workbench at Velocitron, his soft-vinyl-toy production company, but before settling in Tokyo he ran in the circle pits of Kumamoto’s hardcore scene as vocalist for area bands.

For Wilson, a live show is all about theatrics — and underground acts deliver.

“Showa and early ’90s acts felt very posed, not much energy,” he says. “Then a few years ago Momoiro Clover Z came along, jumping around and doing acrobatics. It was dynamic.”

These days Momoiro Clover Z appears in more commercials than concerts. The group has gone mainstream, thanks to a new manager that juiced its act with pro-wrestling antics and cheeky music collaborations. That broke the template and created a new one — idols that don’t sound like idols.

“Music-wise, it’s too much of a stretch from, say, Gauze to AKB48. But someone like Babymetal acts as a bridge. Cute girls doing heavy metal is very grokkable.” And, most importantly, “idols thrive in a dichotomy.”

Such “grokkable” idol acts, meaning they use gimmicks to hook potential fans, include Alice Project (whose members wear glow-in-the-dark “Jason masks”) and Steam Girls (which has a steampunk motif).

Wilson’s grokkable selling point might be his foreigness. Not being Japanese helped him establish a niche: If you want Japanese soft vinyl done right it needs to be done with the domestic infrastructure, making him the go-to guy for international clients. Idols are trickier to put together than mold-injected monsters, but not by much. While chart-toppers have elite production teams, underground units manage to make their mark with one manager and a laptop.

Last March, Wilson posted a casting call to a talent recruitment site asking for paranormal girls to thrash on stage. (“Personality disorders a plus.”) The 30-odd applicants were whittled down to a final four. Sari is a shironuri (white face) performer and Henmi has an eye for choreography. Both teenagers are still in high school and their families approve of their odd hobby. But Kakizaki, the only member with experience as an idol, still hasn’t told her folks, while Tachibana, the self-diagnosed “problem child,” had to call off a photo shoot at an abandoned cable car at her parents’ protest — ironic given that these two are legally adults.

Wilson says hiring an idol is similar to the way any other performer is hired. He established rapport with their families as needed and drafted a standard form contract for transparency — before you ask, he left out the “no boyfriends” clause that many other idol units agree to.

“There’s a misconception that the whole idol thing is a sexual fantasy,” he says. “Maybe that’s true for the gachi koi (true love) units, where fans are creepy and clingy. But those groups advertise themselves as such. And let’s be honest, there are more direct ways to meet that need.”

Wilson views camaraderie between fans as the main motivator.

“At a metal show you never wear the T-shirt of the band (you’re seeing); it’s shallow. But at underground idol events you would want to show support for the unit. Strength in numbers; it’s your gang colors.”

Besides, if the scene was as sketchy as some headlines like to imply, then there might not be as many female fans lining up for shows and handshakes. Acts such as Dempagumi.inc introduced aesthetics and costumes that appeal to teenage girls, not just middle-aged men. The staff of DearStage, a bar where aspiring idols serve short sets and long cocktails, could pass as Harajuku fashion bloggers. Girls who love idols become idols girls love.

But now that he’s backstage, Wilson realizes it’s not all fun and games.

“Seeing how the members prioritize the unit changes your perspective,” he says. “They’re sacrificing study and family time to be here.” And for what? Sari wants to create performance art, Henmi hopes to take the act abroad and Kakizaki vows to quit the idol world if this next gig flops. As a collaborative effort, the members are as responsible for the group’s success as the manager. Depending on which girl you ask, Wilson is either a beacon for their dreams or a bumbling mascot. But he’s someone they all respect.

Necronomidol is still trying to find its sound, though. First single “Toryanse” was a brutal black-metal snowstorm that froze everything it touched, including the mood at the gigs — so Wilson canned it. Most concert organizers use a system where acts are paid for each person there to see them — hence the importance of “Skulls in the Stars.” The track is the group’s most upbeat, crowd-friendly tune to date, and its mix of Italo disco chimes set to retrowave synth is a step toward establishing a new subgenre — and hopefully a core fanbase.

Gimmicks have a short shelf life, so Wilson is rushing to make delivery. After six months most units only have a hand-pressed single to sell at shows, but Necronomidol is already on iTunes and Amazon, with plans to hit record shops to draw in fresh blood rather than cannibalize the idol scene.

Wilson’s plan is ambitious but the end game is ambiguous. If Necronomidol’s solo show in January at Asagaya Loft sells out, then it’s on to bigger venues. If not, well, for now it’s best to focus on the Oct. 30 Halloween bash sponsored by Trash-Up!! magazine.

“Ten years from now I want to be remembered as the group who ‘got it,’ ” Wilson says. “But more than that, I want to take it as far as I can and make it worth the members’ efforts.”

Necronomidol play Trash-Up!! Matsuri: Halloween Night at WWW in Shibuya-ku, Tokyo, on Oct. 30 (6 p.m. start; ¥2,500 in advance; 03-5458-7685). For more information, visit www.necronomidol.com.