Holding up his fretting hand, Bo Ningen guitarist Yuki Tsujii is shaking his head in disbelief as he pauses to consider the last thing that he learned – how to use scissors properly. His index finger is wrapped in a brown plaster and the implications of a sliced digit are almost too horrible for the guitarist to contemplate.

"I accidentally chopped my fingers with scissors and I'd never done that before in my whole life”, he sighs. "It was so stupid and I don't even know how I did it. I thought, scissors are a daily thing and it hadn't occurred to me how dangerous scissors are. Knives are really dangerous and they look that way but no one really pays attention to the dangers of scissors. It hurts a little bit but I've got this plaster on it so it's all sorted.”

It's certainly a lesson that's been taken on board but Bo Ningen is nothing if not a band that has developed its sound through a process of musical self-education. Across two albums – 2010's eponymous debut and 2012's Line The Wall – Bo Ningen have proved themselves to be one of the most interesting proponents of psychedelic music in recent years. Theirs is an extreme variant of the form that's as far away from tangerine dreams and marmalade skies as the sun is from Pluto and one that deals with extreme noise and punishing volume held down by driving and hypnotic rhythms but it's now, with their new album, the appropriately-titled III, that Bo Ningen has pushed against its own barriers.

While their debut was recorded live in the studio and its follow-up built on those foundations, III is Bo Ningen's most textured, layered and thought out release thus far. The excursions into sonic explorations remain firmly entrenched but in place of the huge wall of sound approach and merciless onslaught that has been their stock in-trade are more complex rhythms, a greater sense of interplay between the guitars and wider brush strokes from a bigger sonic palette.

Meeting Yuki Tsujii and his six-string compatriot, the softly spoken Kohhei Matsuda, for mid–afternoon tea in their adopted neighbourhood of Dalston, The Quietus wonders whether the results captured on their new record are the results of evolution or revolution?

"Both,” says Yuki. "In terms of the song writing process it's evolution. We've had much more time doing the songs. We still make songs from jams but this time we had a lot of chat about it.”

"We were more conscious about the production process before going in to the studio,” adds Kohhei.

Yuki nods his head in agreement as he continues, "We were more conscious this time of how we wanted the song to sound like and how it should be. We had a much clearer idea about the songs. We used the same studio and engineer as the last album but we talked the ideas and different aspects through first. We wanted the vocals to have a greater clarity of sound rather than having loads of delays and all the conventional psychedelic effects to make it brighter.”

The vocals do indeed possess a clarity not previously in evidence and, not for the first time, find Bo Ningen working with Savages' vocalist Jehnny Beth. However, what does prove to be a challenging new experience for the band is vocalist and bassist Taigen Kawabe singing in English instead of his native Japanese on the track 'CC'.

"We had to convince Taigen to sing in English which he found it quite difficult but in the end he gave it a try,” explains Kohhei. "Japanese is a very different language to English – it has a different sound. How we speak in Japanese and how we speak in English is very different.”

"Japanese is kind of flat but English has more dynamics to it and it has a different beat and rhythm to it,” elaborates Yuki on the differences between the two languages. "I think, as a result, we have a really nice mixture with Japanese and some bits of English and even though it has the same melody, it sounds quite different. It's something that we'd like to explore in the future but it's a huge challenge for Taigen. That bit that he sung in English makes a huge difference and it makes the song sound really different and in a really good way. It's all new to us and, I guess, the audience.”

As far as Bo Ningen are concerned, this is all grist to the mill. For them, the music that they create is all about exploration and breaking down any perceived notions of categorisation.

"The reason we call our music 'psychedelic' is because it's free but others have described it as 'jazzed-up acid-punk'!” laughs Yuki at the various attempts to pigeonhole the band. "But things get too broad and diverse and abstract, too. But if you call it psychedelic music instead of psychedelic rock then it could be anything. It's quite hard to describe what we do. It's almost impossible to answer the question, 'How do you describe your music?' But being psychedelic is about being open and free.”

Quite how their musical philosophy and approach will be taken and accepted by a wider audience will be put to the test when the quartet support Black Sabbath at Hyde Park this summer. Described by Kohhei as "a dream come true”, Bo Ningen are only too aware that this will be no easy ride.

"We all love Black Sabbath like everyone else does,” states Yuki. "But yes, it's going to be a challenge to play to a new type of audience who are more likely to listen to heavy metal. They probably haven't heard our kind of music before.”

As evidenced by III, Bo Ningen don't just rise to challenges imposed either internally or externally, they conquer them emphatically. Their growth has been organic and one spread by word of mouth about their incendiary live shows and a growing musical vision that can be charted over the course of their three albums. Could just be that Hyde Park will take them further out there with even more converts coming on board for the trip of a lifetime. Time then, to get on the bus.

Bo Ningen III is released via Stolen Recordings on May 11th 2014. To pre-order, go here