Every few months, as if to remind us what a disturbingly odd place Japan is, an alarming Japanese news story explodes online. Western media outlets clamber over each other in their haste to cover the story, with every report of bagel heads, snail facials or ritual head shaving being used as further evidence of a unique Japanese weirdness. A lack of understanding (and, sometimes, basic fact-checking) means that entire stories are lifted, often without critique, and churned into dubious clickbait. Earlier this year, widespread coverage of a supposed eyeball-licking epidemic among Japanese teens that turned out to be a hoax left more than a few editors red-faced.

This round was kicked off with an article in the Guardian looking at reasons behind Japan's rapidly declining population. Since then, sound-bites have been repeated and distorted, and the spiralling birth rate figures have become a hook for a spate of ill-informed, voyeuristic articles that fail to note that the 'weirdness' they see before them is far from representative.

TIME asked whether millions of young people are eschewing sex because they'd rather "manage a virtual candy store in a video game". Vice segued into an exposé of Japan's sex and love industry, taking time to name check "a generation of men obsessed with virtual reality and so intimidated by real women that they prefer cyber girlfriends". They explored 'cuddle cafes', sex dolls, services where you can pay to go on a date with someone dressed as an anime character – all niche industries that would be met with the same bemusement and derision by the average Japanese 20-something that some foreign journalists reserve for East Asia.

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Coverage peaked last Thursday, with a BBC2 documentary entitled 'No sex please, we're Japanese'. While there was some good reporting on what a shrinking society means for Japan, it was almost entirely undermined by an apparent determination to blame "a generation that has never had to grow up".

Presenter Anita Rani's quest to understand the "psyche of the modern Japanese man" leads her to Akihabara: the home of otaku, or geek, culture. As happens all too often, a tiny minority is portrayed as though it were representative of the wider population, and its impact wildly exaggerated. In a supporting article, Rani makes the entirely bogus claim that "One reason for the lack of babies is the emergence of a new breed of Japanese men, the otaku, who love manga, anime and computers – and sometimes show little interest in sex".

I'd love to see someone substantiate this claim. At no point this week – or ever – have I seen statistics to suggest a causal link between the rise of otaku culture and Japan's declining birth rate. (Is the number of otaku rising? Who knows? No one's bothered to do the research.)

And yet, this forms the basic premise of the documentary, which features interviews with two men who believe themselves to be dating video game characters. Rani refers to them as though they are typical Japanese men, rather than part of a subculture within a subculture; the extreme end of a broad category of nerds. Does it need saying that not all of them would want to take a Nintendo-generated schoolgirl on a date?

In what can only be interpreted as a bid to come up with the greatest non-sequitur in BBC documentary history, Rani asks why, when "You've got nerdy, geeky culture all over the world... Japan has the declining birth rate. So what's happening here? Are there just more nerds here?"

The World Bank lists 15 countries with a fertility rate equal to or below that of Japan including Germany, Korea and Romania. I don't remember geeks being credited with the power to suppress entire populations in any of those countries.

When exploring why fewer babies are being born in Japan, journalists would do better to look to social issues such as conservative gender roles, poor protections for working mothers and punishing work conditions that mean men spend very little time at home. Few reports mention the fact that Japan recently fell four places to 105th in world gender parity rankings, according to the WEF Gender Gap Report.

Rani, to her credit, touches upon some of these issues, but only briefly. As is often the case, they are paid lip service only as alternatives to a more salacious headline.

Another, more relevant, phenomenon that's worth discussing is that of 'herbivore boys' or soshokukei danshi: men who subvert traditionally masculine traits and are typically passive in relationships. Unfortunately, though, Rani shows herself to be painfully ill-informed by confusing soshokukei danshi with otaku. It's inevitable that nuances will be lost when you attempt to distil one complex social phenomenon into a paragraph of backdrop to contextualise another; but her assertion that they have "taken on a mole-like existence" is baseless, insulting and woefully ignorant.

It's easy to attack one documentary, and it's easy to offer the defence that its effect will be limited only to its audience. Leaving aside the trust that the BBC commands, what's most upsetting is that this is part of a wider trend. We have a kind of voyeuristic fascination with Japan's strangeness, spurred on by irresponsible journalism and sensationalised headlines. These stories gain traction because they support a simplistic view of East Asia which is at best patronising and at worst overtly racist. Lazy journalism supports these prejudices; every poorly written puff piece and ill-researched documentary serves, as one viewer charmingly put it, as "confirmation of japanese weirdness".

Journalists should strive to challenge, not perpetuate, crude stereotypes. Our collective obsession with portraying Japan as a nation of tech-obsessed sexual deviants dehumanises its citizens and echoes orientalist attitudes that should be long since dead and buried. Enough.

Beckie Smith is a freelance journalist who writes about education, media, feminism and current affairs. She has a degree in Japanese and spent time living in Kyoto as a student. She blogs at ciswhitefemale.wordpress.com.