“When you’re a ‘rock’ guy, there’s something that makes you want to be in the business, as a photographer, working at a label . . . I mean, you’re not going to be a fan of Cat Stevens and all of a sudden decide to be a roadie for Pantera or something. Rock gives you the inspiration to get involved.”

Marty Friedman is a rock guy. The 51-year-old spent much of the 1990s as the lead guitarist in thrash metal pioneers Megadeth, eventually taking the odd-seeming move of decamping from the United States to Japan and settling into a new role as a cheerleader for J-pop. Through his experiences in the Japanese music industry, however, one thing that struck him was just how natural a move that really was.

“Coming from a metal background, what I’ve always noticed is that working in the music business, they’re all metalheads,” Friedman tells The Japan Times. “But there’s no money in metal, so they try so hard to mix it with other things . . . I’ve done so many things where it’s a pop project but (people will say), ‘Make this metal. Play your ass off on this!’ and I love doing it because I love to inject my own thing into everything.”

To Friedman, the enthusiasm and intensity that rock engenders is the key to its appeal and influence rather than the specific sounds it makes, which is perhaps one of the reasons he feels so comfortable working in music in Japan.

“If you’re a metal fan or a rock fan in America, you’ve got to keep it on the down low about listening to pop or dance or rap,” Friedman says. “In Japan, if you like it, you like it. When I played with Momoiro Clover Z, that crowd was louder than any heavy metal crowd. It was just, ‘Raaaargh!’ like Pantera or something. It was insane. I think people (here) are less shy about having an open mind about music, and that’s why musicians are more open to crossing over and stuff like that.”

Friedman’s own enthusiasm when talking about Japanese pop is obvious, and this can sometimes work against him by enabling some critics of his role in the music industry to unfairly dismiss him as a fanboy. Talking to him in the lounge of his hotel in Narita, Chiba Prefecture, as he prepares to embark on a three-week European tour (“That’s the longest I can stay away from Japan before I start needing to come back,” he jokes), he is clearly also deeply knowledgeable about the intricacies of Japanese pop both in terms of the industry’s own practices and the musical tradition.

Admitting that what to him feels like a new kind of musical freedom in J-pop is really just another set of rules and formulae, he is nevertheless intrigued by the nuts and bolts of it, and how the different path of development J-pop has taken has resulted in some fundamentally different rules about how pop songs are written.

“I can totally go into detail about that if you want!” he enthuses with the nervous expression of a man who knows he’s capable of talking for hours on the subject if left unchecked. “You’ve got minyō, enka, kayōkyoku, which are all based on chord voicings that aren’t necessarily heard in American pop, like minor chords with a minor sixth, like the chord that the Beatles end their old songs with, the (Japanese) stick that chord in all kinds of interesting places. And the chord progressions are a little bit closer to white jazz than they are to rock ‘n’ roll. They have minor seventh chords and typical jazz day-one chord progressions in rock songs. This is a big difference: Even an amateur band that’s doing sweaty hard rock will do these happy little jazz tweaks or chord changes that you’d never hear in a rock song.”

He cites the band Noa Noa as an example of the complexity that J-pop can sometimes accommodate, noting that, “You could listen to it on the surface and think it’s just light pop but if you tried to play it, there’s a billion chords in it, the modulations are unusual and there are harmonies all over the place.”

He also mentions with a laugh about the moment he finished writing the song “Kireina Senritsu” (“Pretty Melody”) for J-pop singer Kotoko and listened back, realizing with a note of surprise that “there was no American blood in that song!”

As the rock and idol pop worlds move closer together in Japanese groups, such as in Babymetal and Momoiro Clover Z, it seems in many ways this is the first time that Friedman really makes sense as an entity in the Japanese pop world. But for his new album “Inferno,” he is relishing the chance to unambiguously be a foreigner once more, with the album featuring a series of collaborations with overseas artists ranging from latin guitar duo Rodrigo y Gabriela to Jorgen Munkeby from Nordic jazz-metal band Shining, the latter of which turned out the be one of Friedman’s personal highlights on the album for reasons he himself found surprising.

“Shining are going to be the new Nine Inch Nails, I think. It’s super modern, super heavy and the music is super catchy . . . and there’s a sax in there,” he says. “To me, as a metaller, sax is an alien instrument, I don’t like it. But I listen to his music and I know this guy will get it. I told him to go crazy, I’ll pick one of your sax phrases and then loop it. I took the sax first and moved it around and had my way with it! I really despised sax, it’s the easy listening instrument, but I knew when I heard him I had to do it and it turned out to be one of my favorite songs on the record.”

As with his experiences in J-pop, it’s the enthusiasm that comes from rock that lies at the core of the appeal these collaborations hold for Friedman. Living a rather cocooned existence in the Japanese music scene, he admits to having lost touch with what’s happening in music in the rest of the world, so when his American record company sent him a list of quotes from young and contemporary musicians citing him as an influence, he was both embarrassed and intrigued.

“I remember one time (German guitarist) Michael Schenker came to my house in Arizona unannounced and said, ‘I wanna do this project together,’ ” he says. “I was a fan of his since I was little, so to have this guy ask me to do a project with him? I just remember being so excited and I wanted to bring my super A-game to what we did. We did some stuff and it never got released or anything, but I just remember that feeling when I was working on it, and if I could just give some of these guys that feeling and get the fruits of their labor and that enthusiasm, man, it could be something amazing.”

The album also gave him the opportunity to at least temporarily shed the baggage of his position as a Japanese media celebrity, a status he confesses that he has a love-hate relationship with.

“It opens tons of doors and allows me to do whatever I want musically,” he says, “but the downside is that while a lot of people know me, they don’t know I play music.”

Instead, with “Inferno” he is able to step out from behind the scenes of the idol business and reassert his identity as a long-haired guitar colossus. For Friedman, however, the important thing is to keep up that enthusiasm and keep finding new ways to move forward.

“When you do music this long, you’ve got to do something that inspires you to keep going, to challenge yourself,” he declares with finality. “Otherwise you’re done, your career is over at that point. I’m constantly trying to do something new.”

Marty Friedman’s “Inferno” is in stores now. For more information, visit www.martyfriedman.com.