Beginning this weekend at the Sundance Film Festival, when Yoshiki, a founding member and leader of X Japan, will perform with a string quartet at the first-ever Sundance Base Camp party on Friday night, the prog/metal band will make another attempt to break it big in the U.S. Part of that strategy is “We Are X,” a documentary that’s having its world premiere in Park City on Saturday, Jan. 23 as part of the fest’s non-fiction slate.

For an Asian band, even one that has sold 30 million recordings, to break it big in the states is no mean feat. As the film points out, bands that don’t sing in English, and even exhibit a mild accent — that is if it’s not British, Irish or Australian — have a pretty tough time gaining mainstream success outside of their own countries. Their latest album, their first to be sung completely in English, is scheduled to be released later this year with a yet-to-be-determined label.

The film charts the growth of the band, pioneers of the “Visual-Kei” phenomenon that mixes KISS-like theatrics with everything from glam to speed-metal, from its early years in the late ’80s to its big western coming-out party in October of 2014, when they sold out Madison Square Garden. Along the way there’s much high drama, mostly dealing with premature death, including that of Yoshiki’s father, which had a profound effect on him growing up, and two of his band mates, one from suicide. There was also the business of his lead singer Toshi being “brainwashed” by a cult, leading to his departure from the band in 1997.

“If you look at the back story, it’s one of those ‘so crazy you couldn’t make it up’ sorts of things,” says Stephen Kijak, the film’s director. Kijak, who was recruited for the film by producer John Battsek — with whom he had worked on two other music docs, “Stones in Exile” and last year’s “Jaco” — says he knew nothing about the group going in. “It was fun for me,” he adds, “as opposed to doing the kind of fanboy homage movie; this was a real learning experience.”

The androgynous Yoshiki, who studied classical piano as a boy and eventually switched back and forth between keyboards and drums in X Japan, is a rather rare and fragile bird, struggling with health issues and showing his emotions easily, both on stage and in interviews. He was convinced to cooperate with the filmmakers by his agent, WME’s Marc Geiger. And according to Kijak, was completely hands off during the process.

“It’s a very interesting film but at the same time kind of painful for me,” says Yoshiki by phone. He said he “cried like 15 times” while watching it the first time.

Kijak had plenty of material to work with, having followed the band around prior to their Madison Square Garden extravaganza, including a couple of sold-out warm-up shows at the 17,000-seat Yokohama Arena in Japan. “I’ve never seen such pandemonium,” he says.

“This is a man who’s been documenting himself and his band for decades now,” adds Kijak, “he’d have cameras rolling on everything. So we really did a deep, deep dive and found some really great private moments that will give fans a real eye-opening look into the nooks and crannies of Yoshiki’s secret life.”

Kijak also had access to footage shot by 30 cameras during their so-called farewell performance at the Tokyo Dome on New Year’s Eve of 1997.

“We had all of the cameras so we could go in there and get microscopic with it and slow the pace down, and mine it for the drama, because there was a lot happening between the members.”

It’s the kind of melodrama that music channel VH1 has made a cottage industry out of, but don’t expect the usual sex, drugs and rock ’n’ tropes associated with such endeavors. Curiously, “We Are X” dispenses with the sex and drugs part.

“Lord knows we never came across it in the narrative,” explains Kijak. “It’s really more about death than anything — the specter of death, suicide… this kind of haunted character that Yoshiki becomes. It felt more mythological in a lot of ways, and we wanted to push it more into that kind of dream-like space, exploring the exalted, heightened, doomed rock star.”

When asked about the more bacchanalian aspects of his life with the band, Yoshiki demurs. “Being in Japan, everything is very strict,” he explained over the phone. “Drugs are a no no, so we don’t really do drugs. We drank a lot. It wasn’t a part of our lives.”

He describes the upcoming album as “really heavy, edgy, at the same time there are some catchy songs and some soft ballads.”

Passion Pictures, the production unit behind the film, has no distributor in place. And at a time when music docs are seemingly being made hand over fist but rarely find success on the theatrical circuit, “We Are X’s” fate, and maybe even that of the band, may very well rest on its reception at Sundance.

“With the Backstreet Boys film I did (‘Show ’Em What You’re Made Of’),” says Kijak, “we went right to the fans.” It only grossed $282,000 in theaters but topped the documentary charts on iTunes and Google Playstore. “It was a bigger release than anything I’ve ever worked on,” adds Kijak. “You can make a great success of a film going fan-first.”