There’s a basic disconnect at the heart of Tokyo’s Nisennenmondai. A series of small contradictions run through nearly all aspects of what the instrumental trio does, but they add up to make it one of the most intriguing bands to come out of Japan’s underground and experimental-rock scene in the past decade.

It’s a contradiction that you might be able to see when they go on stage in the cavernous environs of Shin-Kiba Studio Coast for this year’s Neutralnation music festival, because as Nisennenmondai get more and more well known, ascending to the status of Japan’s international experimental-music royalty alongside the likes of Boris, Boredoms and Acid Mothers Temple, there remains something intimate, introverted and impenetrable about the band.

On stage in front of hundreds of people, the group often forms a tight circle, facing inward toward each other, rarely even looking at — let alone communicating with — the audience. It gives a sense of a band absorbed in a world of its own, although according to drummer Sayaka “Hime” Himeno, speaking (naturally) from behind a veil of e-mail, the reason is more prosaic: “Simply, that’s the easiest way for us to play. Plus we’re all very shy.”

It’s certainly a style of music in fitting with the group’s internal dynamics: monotonous, slowly building grooves and hooks being constructed in layers and subtle signals between members determining when a track like “Mirrorball” will lurch forward from taut, repressed energy into expansive psychedelia, or when the earsplitting guitar noise of “Ikkyokume” will suddenly drop out and give way to one of Japanese rock’s most ferocious drum solos.

And it’s no coincidence that perhaps the most successful recorded iteration of the band’s sound so far has been 2011’s “Nisennenmondai Live!!!” double album. A live show is definitely the best place to experience Nisennenmondai’s sound, because for all the group’s introverted stage presence, the music is fiercely expressive at times.

“It’s true that live performance is the most important aspect of our music,” agrees Himeno. “People can not only get the visual side of the group, but they can also get our power and energy.”

Visuals and atmosphere are clearly things Nisennenmondai takes into careful consideration, with the group occasionally incorporating visual and theatrical quirks into its performances (I have eerie memories of one set that was performed while the members wore macabre masks). The sense of theater extends to the environment in which the gigs take place, too.

“Of course big venues have the advantage that audiences can enjoy dynamic sounds through a good sound system,” says Himeno. “But for us, we like to play places like warehouses where the bands and audience can enjoy the atmosphere of the space together — where there might be noise coming, people dancing, bands playing in a kind of informal atmosphere.”

After Neutralnation, Nisennenmondai’s next live date will be as far removed as it’s possible to be from the slick professionalism of Studio Coast. The group is producing its own event in December at the tiny Ochiai Soup, where the lack of a stage means there is no separation between artists and audience, and Himeno’s vision of the perfect atmosphere for a Nisennenmondai show might be realized.

As with all aspects of Nisennenmondai’s work, Himeno describes the process of putting together shows, music and performances as “trial and error,” constantly seeking out the little things that work, experimenting with new things and moving forward with what the members like. It’s an approach that they have been able to develop through the avenue of their own Bijin Records label, where new ideas occasionally make their way into the public domain in a limited, trial fashion via CD/R releases distributed through small independent record shops such as the famous/notorious Enban in the Koenji area. These snippets usually come before appearing as part of a full album at a later date.

“We used to release on cassettes,” explains Himeno, “but now CD/R is the most convenient format for us. We like the idea of vinyl records and some day we’d like to release something like that.”

Staying true to an independent, DIY ethos, it’s also a label through which the band has released material by artists such as old university friends Fukuro and Osaka experimental weirdniks Oshiripenpenz.

“We thought the sound and meaning of the word ‘bijin‘ (‘beautiful person’) was good,” says Himeno. “There might be some people who feel uncomfortable with the word, but we don’t mean it as just someone’s appearance, we mean beautiful in a wider sense. That’s our aim.”

Himeno is able to promise the group will debut new material soon, but she can only talk in vague terms about the future. Despite taking such a hands-on approach to all aspects of their work, from the construction of the sound to the organization of the shows to the release of the music, there’s a sense that with the experimental, trial-error approach they take, Nisennenmondai’s members themselves never really know where they’re going next.

But perhaps for a group who stand stock still while at the same time charging forward at breakneck speed, who reach out to ever wider audiences across Europe and the U.S. while they stick close to their small, intimate circle of friends and fans at home, and who turn their backs on their audience while at the same time inviting them ever closer, this is just one more contradiction adding to what already makes them such a fascinating and unique band.

Nisennenmondai plays Neutralnation at Shin-Kiba Studio Coast in Koto-ku, Tokyo, on Nov. 11 (the event starts at 1 p.m., Nisennenmondai plays at 2:05 p.m.). Tickets cost ¥5,000 in advance (¥6,000 at the door; ¥2,000 for those under 18). For more information, visit www.neutralnation.net or www.nisennenmondai.com .