Two years ago, Underworld duo Karl Hyde and Rick Smith had an epiphany. After more than three decades of working together — through some unremittingly lean early years; an epoch-defining, mega-selling turn in the 1990s; soundtracking the London Olympics opening ceremony, and a fractured and increasingly separate recent past — the pair suddenly realized a convenient truth. In touring their groundbreaking 1994 album “Dubnobasswithmyheadman,” a record that shifted the parameters of what was possible in dance music, the two men figured out that not only did they appreciate each other, they also liked each other.

“It had to happen eventually,” Hyde, the band’s engaging frontman, tells me when I meet him one Friday afternoon in a hip central London bar. “And there are lots of things that have contributed to it. But the bass line is that after such a long time we have found this undiscovered connection, a symbiotic relationship that’s been made clear to us. We’re very different to one and another and we both cover areas that the other can’t or doesn’t want to or hates or whatever. But we’ve realized that is a strength.”

It took a creative absence after 2010’s “Barking” — Hyde released two albums with Brian Eno as well as a solo effort: Smith worked with film director Dany Boyle — to draw that conclusion.

“You become snow blind to what it is that the other person does that is so good and then you become complacent about it,” Hyde says. “We’ve found another way of looking at each other.” He lets go a smile as wide as the stripes on his Breton top. “We’ve become inseparable now, and it’s really great. It freaked people out at first, they thought we were hatching a plot!”

There was no grand plan, but Hyde and Smith’s recoupling has certainly worked: Underworld is a band reborn. It is evident in Hyde’s manner, sitting at our booth and sipping a non-alcoholic ginger beer, he speaks enthusiastically and at length about the act’s long history (unthinkably given his youthfulness, not to mention his engrossing stage presence, he turns 60 next year). But more so in new album “Barbara Barbara, We Face a Shining Future,” a record that sees Hyde and Smith sounding positively flourishing 35 years on. A kaleidoscopic flow of light and dark, heart and soul, euphoria and contemplation, it is their best work since the ’90s.

“Barbara Barbara, We Face a Shining Future” (the title inspired by one of the last things Smith’s dad said to his mother on his deathbed) was the result of the pair deciding to work in an untested manner after making “too many records file sharing, working alone, talking over the phone.” Meeting two days a week with no conceived ideas, the pair followed their senses. “Rick had a saying: ‘You are enough.’ So that was the attitude,” Hyde says. “We would just get together and see what happened, even if we only had an hour or I hadn’t brought lyrics. And it was great there was no expectation. I was almost fascist about protecting us from Underworld. I didn’t want us to think about Underworld. I just wanted to play with my mate. It enabled me to challenge myself without any preconceptions about old baggage.”

If the songs proved the process right, from pounding opener “I Exhale” to the gentle beauty of “Ova Nova,” Hyde’s trademark lyrics — beat poetry via the streets of Essex — once again startle. Since he stopped drinking in 1999, Hyde is in a cafe by 7:30 a.m. every morning (“I like the discipline, I like the structure”), looking and listening, noting and photographing things he’s “instinctively drawn to.” As he travels, snatches of overhead conversations and every day, scattered observations (“sharp shadow / clean dirt / metropoles / statuesque”) make their way into Underworld songs. Yet in doing so, they also reveal to Hyde his true emotions. Art is used to articulate thoughts.

“I don’t know what I’m thinking,” he says. “So I make marks, jot words, make music or visual art, and I leave the room, walk back in like a spectator and then go, ‘Whoa, Jesus! OK, fair enough, that’s what I was thinking.’ I can’t describe my emotions, I can only describe them through things I collect. If somebody asks me how I feel I can go ‘s—-‘ or ‘happy’ or ‘OK.’ But can I articulate that? No, not really. So I use art to discover how I feel.”

Hyde has worked like that since the late ’80s, by which time he and Smith (who met in Cardiff in 1981) had already moved on to Underworld after limited success with ’80s rock outfit Fleur. In the thrill-seeking acid house era, not only did Underworld prove that substance need not be confined to one’s extracurricular intake, the pair (and initially DJ Darren Emerson) rewrote the rules on how a dance act could be successful. “We didn’t have a contract. We said we’d never again be part of any strategy that stood between us and our audience or told us what to do or took away idiosyncrasies. We didn’t need an A&R man telling us what to do or where the scene was — we were in the scene. It was the same with my role. I was a frontman playing a supporting role. There weren’t any singers in dance bands, so I decided it was my job to let the groove take me where to pitch it and the emotions that need to be generated. My job was never to take attention.”

Hyde unwittingly became the centrer of it after “Born Slippy” catapulted Underworld into the charts in 1996, aided by its inclusion in the cult classic “Trainspotting,” forcing Hyde to finally “become an archetypical frontman.” Such was the track’s ubiquity, Underworld was still shifting units long after its Britpop contemporaries had stalled. After Emerson’s departure in 2000, a couple of lesser albums and personal animosities had seemed to slowly take their toll.

It makes Underworld’s creative and commercial resurgence all the more welcome. The campaign for “Barbara Barbara” has been one highlight after another: two superlative, “very special” shows at London’s Roundhouse (which not even a mid-gig evacuation could ruin), a mammoth Friday night headline set at Glastonbury, and in Japan, a gig for 250 people on the roof of retailer Parco, broadcast on the big screens at Shibuya crossing.

“It was incredible. It was also on the radio, in VR and broadcast to the speakers on the telegraph poles in the street,” Hyde says. “Tokyo is like another home to me, so it was special.” Hyde seems genuinely nonplussed.

“It’s blown me away these last two years. Why? Why, why, why? There is a renaissance around our popularity and people know something beyond my understanding. I accept it, but don’t take it for granted. We’ll keep going on our journey. We’re beyond doing this for ego — I’m doing this for the art.”

Underworld plays Summer Sonic’s Marine Stage at QVC Marine Field in Tokyo on Aug. 20 and the Ocean Stage at Maishima in Osaka on Aug. 21. One-day tickets to the festival cost ¥16,800, two-day tickets cost ¥30,500 (¥14,000 and ¥25,500 in Osaka). For more information on the event or the band, visit www.summersonic.com or www.underworldlive.com.

In line with COVID-19 guidelines, the government is strongly requesting that residents and visitors exercise caution if they choose to visit bars, restaurants, music venues and other public spaces.