There’s something curious happening on “Nemutte,” the sophomore album by Tokyo-based instrumental trio Kafka’s Ibiki. When it performs live, the group specializes in long, patiently evolving improvisations that occupy a liminal zone between jazz, ambient, minimalism and experimental rock.

One such performance, at SuperDeluxe in Tokyo, was captured on the band’s engrossing debut album from 2014, “Okite” (“Wake Up”). If you were to leave “Nemutte” (“Go to Sleep”) playing in the background while doing something else, you might mistake it for more of the same. But closer listening reveals a hive of sonic activity that would be all but impossible for the group to achieve in real-time.

In fact, the album is a canny composite, stitched together from studio improvisations by Kafka’s Ibiki’s in-house producer, multi-instrumentalist Jim O’Rourke. So radically did he rework the material that his band mates, keyboardist Eiko Ishibashi and drummer Tatsuhisa Yamamoto, say they didn’t even recognize themselves at first.

“I was like, ‘Who’s this?'” Yamamoto recalls. “I’m not kidding: I really had no idea.”

“I never know if it’s me playing or not,” agrees Ishibashi. “It’s always like that with Kafka’s Ibiki. Whenever Tatsu plays a recording from one of our shows in the car, I’m always asking who it is.”

The group, which took its name from a studio owner who used to sleep noisily through their sessions (“ibiki” is Japanese for “snore”), is just one of a number of musical projects for the trio. Over the past few years, they’ve come to resemble the classic session bands of old.

Often working with bassist Toshiaki Sudoh and string player Atsuko Hatano, they form the backup band when Ishibashi and O’Rourke do concerts of their own singer-songwriter material; until recently, they were the regular live band for acid-folk singer Kenta Maeno as well. All three are also active on the Japanese improv scene, and can often be heard playing together in sessions alongside notable figures from the realms of free jazz and experimental music.

“We don’t think of it in terms of being a ‘main project’ or anything,” O’Rourke says of Kafka’s Ibiki. (The interview was conducted in Japanese, which he speaks fluently.) “Compared to the other things we do, though — I don’t want to say this is the easiest, but there’s no practicing involved. We go to the venue. We play. We go home.”

“There’s no set list,” interjects Yamamoto.

“First set, second set,” says O’Rourke, laughing.

The trio’s other musical pursuits have proved to be a blessing. While they were in the studio to record Ishibashi’s 2014 solo album, “Car and Freezer,” they captured a couple of hours’ worth of improvisation together, which O’Rourke recorded to multi-track. When they returned to the studio a year later, this time for O’Rourke’s “Simple Songs” (released in 2015), the band recorded another session, playing along to a rough mix of their previous engagement.

O’Rourke then took these recordings and wildly reconfigured them, splicing together individual instrumental tracks and sections of ensemble playing to create a richly detailed phantasmagoria. He describes listening to the original recordings as if to someone’s voice, asking what they wanted to say, and then rearranging them repeatedly until the signal became clearer.

“If we’d wanted to make an album that captured the feeling of our shows, we would’ve recorded it that way,” O’Rourke says. “We wanted to handle things differently.”

It’s a similar approach to the one he took with his 1990s band Brise-Glace, whose “When in Vanitas…” was stitched together from improvised sessions. However, he traces his interest in such methods back to hearing Frank Zappa’s 1979 album “Sheik Yerbouti” at a formative age. On the song “Rubber Shirt,” Zappa took bass and drum tracks that had been recorded in completely different contexts and combined them to create a new piece, in a technique that he dubbed “xenochrony.”

“I remember that well: being 10 years old and thinking, ‘Wow, you can do that?’ ” O’Rourke recalls. “From then on, I considered it normal: it was another possibility you had when mixing.”

Heard over a good set of speakers or headphones, “Nemutte” is deeply engrossing, the kind of album that reveals something different each time you play it. Yamamoto isn’t exaggerating when he describes it as a “3-D mix”: the instruments hang in seemingly infinite space, snare rolls panning from one speaker to another while whispery traces of percussion, synthesizer and processed guitar shimmer in the distance.

Ishibashi compares the album to the documentaries of Werner Herzog, in which the German filmmaker uses obvious stylization — and, sometimes, outright fakery — to expose what he calls “poetic, ecstatic truth.”

“It may have started off as a documentary, but he’ll exaggerate things a little in order to make them more real,” she says. “It’s not a lie, but by dramatizing things he’s able to reveal a deeper reality. I think it’s close to what Jim did with the mix this time around.”

It’s a telling comparison. Yamamoto and Ishibashi may not have recognized themselves when they first heard the album, but “Nemutte” comes closer to distilling the essence of Kafka’s Ibiki than any single live recording could.

There’s a rare alchemy in the band’s performances, where it can feel at times like one member senses where the others are heading even before they know it themselves. It would be easy to assume that this intuition comes from having spent so much time playing together in other contexts, but the group’s members insist that Kafka’s Ibiki stands apart from their other activities.

“We’re deliberately treating this as a separate space, unconnected with anything else,” says O’Rourke.

“We spend a lot of time together,” says Ishibashi, musing on the theme. “When we’re recording, everyone stays over at the studio, and at nighttime we’ll all be drinking together and listening to music or watching YouTube. We’re exchanging a lot of stuff with each other, so if somebody starts to head in one direction (when we play), the others will often follow naturally.”

“Nemutte” is out now. Kafka’s Ibiki plays Super Deluxe in Minato-ku, Tokyo, on Dec. 1 (7:30 p.m. start; ¥3,000 in advance; 03-5412-0515). For more information, visit www.kafkasibiki.bandcamp.com

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