Asako Yusuki, centre, signing copies of Butter in Piccadilly Waterstones last week

HERS has been the name on the yellow book with a cow on its front cover gripped by thousands of Londoners since being translated into English.

And yet – by her own admission – Asako Yusuki is not celebrated in her home country of Japan, where her international hit Butter was first published.

Having sold almost half a million copies in the UK, however, she now finds herself on a global book tour. In Waterstones in Piccadilly last week, every seat in the house was filled, with tickets already sold out weeks before the author was due to appear.

When asked to introduce herself, Asako simply says: “My name is Asako, I’m a writer, but I’m not popular in Japan, so I’m surprised to be in a bookshop in London.” She pauses. “I don’t want to go back to Japan, all Japanese ignore me,” she jokes.

Based on a real murder case of the “Konkatsu Killer,” Butter tells the story of Kajii, who is behind bars for allegedly killing three of her former lovers, and the journalist Rika who is desperate to get the real story.

Asako’s novel is not however a traditional whodunit. Instead she has taken media coverage of the case – laced with misogyny and fatphobia – as the guiding themes.

“That case was sensationally reported. There was a lot of buzz around the case itself,” Asako said. “I was more interested in the media coverage of it, and also the structure of Japanese media itself. So I would say I really wanted to focus on that side of Japanese society as well as how much Japanese people have internalised that media reporting, that trend of media reporting.”

The product has been read in the UK as a searing exposé of Japanese beauty standards and the physical and mental burden women must take on in order to be seen as hard-working, worthy, or simply just acceptable.

Asako said: “It wasn’t my intention to expose the misogynistic element in Japan. I was merely writing an everyday life in Japan, this is what most women go through.”

In her quest to obtain an exclusive interview with the gourmet chef-turned-murderer behind bars, Rika writes to Kajii asking for a recipe. Their relationship develops into one of mentor-mentee as Kajii encourages Rika to explore the culinary world around her – tasting everything from rice with good butter to the delights of the French restaurant scene in Tokyo – and come back and describe the sensations to her.

Here, the descriptions of food sometimes seem, to a British reader, other-worldly.

“As the warm sea urchin was crushed on the surface of her tongue, it was transformed into sea-flavoured cream that blended seamlessly with the similarly rich taste of the flan pastry, redolent with egg yolk,” writes Asako.

Translator Polly Barton said this was one of the most difficult things to get right. “I wanted to have it feel incredibly luscious and sensual, but not tipping over into that food-porny territory,” she said. “There is a culture in Japan of describing food in a way that, particularly to a British audience, maybe seems a bit extreme. So striking that balance is something I was thinking about a lot.”

As Rika starts to eat, she also puts on weight, and is criticised by everyone around her – her boyfriend, her best friend, her boss.

Her own experience leads her to reflect on the impossible ways the women in her life must contort themselves to please the men around them. “The quickest way for a modern Japanese woman to gain the love of a man is to become corpse-like,” she concludes.

Butter is a book that rests on its female characters and their complexities, they are rude to each other, they betray each other, they are responsible at times for propping up the patriarchal standards that exist to crush them. This, according to Asako, is one of the reasons why the book was less well received in Japan. “In Japan, if your female characters are not working towards the same goal, you are seen as part of the problem,” she said.

In London, we seem to be a little more forgiving of these women’s flaws. We know how difficult it is to exist in a world that has a lot of unspoken rules and regulations. And this is perhaps why Butter has proved so popular with an English-speaking audience. Your boss might not directly tell you that you have put on weight, but having to care that people might notice can be just as oppressive.

• Butter. By Asako Yuzuki (translated by Polly Barton), 4th Estate, £14.99

AloJapan.com