This passion is reflected in the decor of a showroom-like space on the ground floor of her home. Yellow walls and a pink-and-green polka dot floor form the backdrop for an eclectic collection of film memorabilia and vintage toys. There are life-size replicas of C-3PO and Iron Man, shelves filled with Barbies still in their original boxes, and a model of Gundam assembled by Yagi herself. Spiderman flies overhead, and a slightly scaled-down version of a London phone booth is filled with DVDs.

But there is also the shelf full of shoes, which gives a glimpse into the petite 62-year-old’s personal style. This is where Yagi displays the pairs she reserves mainly for special occasions, such as the Charlotte Olympia T-straps with larger-than-life platforms, and the Dolce & Gabbana pumps with a sculpted figurine of a Sicilian woman as the heel. Surprisingly, she wears them all.

“I don’t consider shoes you can’t walk in to even be shoes,” she says. “They are designed with one purpose in mind, so if they can’t fulfil that purpose then they aren’t what they are intended to be.”

Admittedly, Yagi’s idea of shoes that are easy to walk in differs from most people’s. Impressively agile, she works out every morning; she always stands up when putting on her shoes in order to maintain good balance; and she often walks up to 10 kilometres a day in heels that can be 10-centimetres tall.

With such an explosion of colour and print in her home and her wardrobe, one would assume that Yagi has been honing her style and collecting pieces for her entire life, but this is not the case.

“I wasn’t always interested in fashion. But even as a child, I [was] fascinated by the concept of life and death. So because life is short, I wanted to do something to improve myself and to make the most of it,” she says. “I started with the inside, by reading books and visiting museums. Then when I was in my 30s and my kids were at the ages where they could be a bit more independent, I started thinking about the outside, too.”

This sparked Yagi’s interest in fashion, and she went from dressing in simple jeans and T-shirts to shopping at designer boutiques. Still, she says that for the first five years she always wore all black, as she didn’t have the confidence or experience to put together different colours or prints. Even then her favourite brand was Dolce & Gabbana, and she says that as the brand’s pieces became more colourful, so did her own personal style. Today, Dolce & Gabbana remains on the top of her list, and some of the other brands she favours include Fendi, Sonia Rykiel, and Balenciaga.

Yagi says spring and autumn are her favourite seasons, as she enjoys being able to combine a variety of different pieces into her outfits. “I don’t have very many warm winter clothes, because even when it’s cold out, I prefer to just layer together many thin fabrics,” she says.

Yagi, who works full time at the shipping company she runs with her husband, only gets about four hours of sleep a night – she says it’s all she needs. She maintains a remarkable list of hobbies that includes making perfume, sewing some of her own clothes and embellishing traditional Japanese okobo sandals with flowers, beads and appliqué patches.

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“I love to walk to Ginza and look at all the storefront windows,” she says. “There I see pieces I like and I start to think what I would wear them with. If I can’t find what I want in a shop, I’ll make it myself.”

One entire floor of Yagi’s house is used as her personal wardrobe, with rack upon rack of clothes. All her clothes are hung on black plastic hangers and are organised by colour. There are also bookshelves overflowing with handbags, tables covered in hair accessories and headpieces, and drawers filled with jewellery. The sheer volume of the collection is incredible to behold, but Yagi says she remembers everything she owns and she rarely gets rid of pieces.

“I buy the things that I like, and since I continue to like them, I generally don’t give them away very often,” she says.

For luxury brands, Yagi would appear to be a dream client. Not only is she enthusiastic about fashion and wears what she buys, she also makes it easy for brands to sell to her.

Since 2010, she has been putting together monthly booklets of her style, showing every one of the outfits she wore the previous month, while also sharing glimpses into her life, such as parties, events and media appearances. She does all the photography, writes the text, cuts out and arranges the images, and then prints, trims, and staples together each booklet.

Then she hands these out to staff at the stores and showrooms she visits in order to give salespeople a better idea of the clothes that she likes and how she puts them together. This is all in addition to the daily Instagram posts of her outfits, which use different photos altogether.

“I’m just looking for the things that I like, and it’s a given that I’m going to wear them out on the town, so I think from the viewpoint of the brands, I’m a customer that has a lot of value,” Yagi says. “They can get ideas from me, and they know that I really do love fashion. So we respect one another.”