When Katie Green launched KÉJI last year, she knew the competition would be fierce. But she had a point to make. “Everyone was saying fashion denim has had its moment,” says Green. “There’s so much on the market that’s called denim but it’s not really denim. What I try to do is remove ‘trend’ elements and treat denim as a tailoring fabric.”

Call them the anti-jeggings, if you will. KÉJI’s no stretch, Japanese-sourced, “real” denim pieces take the material back to its utilitarian roots, fusing the sharp tailoring of early 20th century workwear with sportswear elements and volume. Her debut collection was a tightly edited, 11-piece collection influenced by WWII-era American sportswear designer Claire McCardell and the sharp lines of Japanese erotic woodblock prints.

Looks from KÉJI’s autumn/winter 2016 collection

The drawstring jackets, voluminous trousers and tailored shorts — all made with indigo blue denim — are what Green says is her modern version of the double-denim ensemble. “It’s been really freeing to focus on one particular fabric and push the boundaries as to what we can achieve with it,” she says, inside the Bethnal Green studio she shares with fellow designers. “Fashion is quite fickle at the moment but something like a great pair of jeans can last forever in a woman’s wardrobe.”

Her approach to denim is, she says,  “slow”. “I work with a mill that still uses machines from the 1950s and everything is in quite small runs. And we use chemical-free, indigo dye to achieve that ‘true’ blue colour,” says Green. “It’s my reaction to all this fast fashion and trend-driven products out there.”

Hong Kong-raised and London-based, the former Net-a-Porter buyer attributes her international background to the eclectic mix of influences seen in her designs. “I’m a complete mix — a blonde from Hong Kong who feels as much from Asia as anywhere else,” she says. The Hong Kong native (who speaks fluent Mandarin and Cantonese) moved to London eight years ago and assisted Katie Grand at Love magazine, before the three-year stint at Net-a-Porter. In just over a year, her stockists now include Net-a-Porter, Selfridges, Barneys Japan and The Store x Soho House Berlin. “KÉJI, the name itself, could be Japanese, or it could be French with the accent. A lot of people don’t understand where it comes from and I love that.” In fact, KÉJI is Green’s initials spelt out phonetically.

Looks from KÉJI’s autumn/winter 2016 collection

And it is this captivating ambiguity that has drawn a wide range of customers, just three seasons in. “Mrs. B [Joan Burstein, founder of Browns], who has just had her 90th birthday, is one of my customers. And then we have teenagers wearing the clothes too. I think anyone can wear it.”

Having started with a clear, focused niche, Green says her ambition for KÉJI is for it to evolve into a lifestyle brand. Indeed, her upcoming autumn/winter 2016 collection experiments with new fabric, including waterproof velvet, as well as new influences — mainly après-ski and 1960s futurism. “Whether it’s denim or velvet, what I really want to do with the label is to put energy and detail back into everyday clothing,” she says. “I want to make clothes you can live in.”

Interview by Jainnie Cho