The collection is also very affordable. "I know that many of my fans are young - say 12, 14, 16 or older - and they think because I'm in high-fashion, it will be expensive. But it's not," she says. I.T boss Sham Karwai, who last week was celebrating I.T's 30th anniversary celebrations in Hong Kong, says that as long as Mizuhara continues to make interesting projects happen, the retailer will be happy to sell OK on a permanent basis. Part of Mizuhara's crossover appeal is that she spends half of her life having couture imposed upon her - and knows all too well the rigors of wearing it, making her entirely relatable to her fans.

So what about the rigors of wearing a traditional Japanese yukata, something Mizuhara included in her OK collection. What's her style advice to a bunch of young Chinese girls who've never tried the idea before? "Well, two ways," she explains. "It's a whole set with three must-have items: the geta sandals, the obi (sash) - which is like a corset - and the yukata. So first, buy the whole set and wear it once. It's nice to try it once if you haven't. Otherwise, you should do it traditional, but mix it with accessories. So wear the obi and yukata with heels, or try off-shoulder and put a flip-dress underneath. You can do whatever you want!"

A tagline that reads like Mizuhara's mantra. The sisters have created an accompanying book that involves their Tokyo friends. "We wanted to make the book very special and artsy, with the art and visuals being very creative," says Mizuhara. "So we used (Tokyo photographer) Monika Mogi; she's my best friend and so talented."

All of which gives OK a collective sense. "I think OK is like a platform for girls to have a feeling of belonging and friendship, and I feel like we didn't really have that feeling in Asia yet; it's a sort of girl-power feeling to the brand," says Mizuhara. With openings in Hong Kong, Taiwan and China, OK is launching in Indonesia and Thailand soon. "So far, it's been amazing to see all of these girls enjoying our products and just being themselves."

Mizuhara grew up in pre-Instagram times reading magazines and being seduced by the lifestyle of what she saw. "I was inspired by all the models," she says. "They were living a different life and that's what I'm trying to do now."