All photographs courtesy of Dana Distortion/ Amuse Inc.

In his book The Undivided Past, David Cannadine argues that while historians have the habit of categorising people into broad, mutually-exclusive and adversarial groups by gender, religion, race, class, nationality and so on, in practice the world is far more fluid and collaborative than their Manichean models purport. Mankind, says Cannadine, is made up of individuals who share a common humanity and really just want to get along (man). And for the most part in fact, people have got along pretty damn well and actually still do, even in spite of our regular clashes and conflicts which inevitably draw attention away from the more humdrum, everyday instances of constructive and amicable social cohesion.

The historian and the music writer are very similar beasts. Both hoard vast archives of largely useless material, neither party looks remotely dignified when wearing a leather jacket (naturally, corduroy is the way to go) and journos, too, are prone to lumping bands and fans together into categories, genres, subcultures and scenes. A lot of this is lazy fabrication and generalisation as well. One could argue that hippies and punks weren't so different after all (just look at Crass). Moments of unpleasant violence between mods and rockers, such as the Brighton bank holiday beach brawl of 1964, were neither as large-scale nor frequent as media exaggeration purported. Come the 1990s' mod revival that was Britpop, despite the attempts of the press to brainwash us into thinking that credible music could only be made by white Englishmen with guitars and bowl haircuts, back then I actually owned cassettes by Mariah Carey, TLC, David Holmes, Kenickie, Ben Folds 5 AND Creed. Just call me Mr Cosmopolitan.

Since then the internet, playlist culture and globalisation have all contributed to the ongoing demise of music "tribes" so that people are now more likely than ever to listen to, say, terrifying speed metal one moment and shiny happy J-pop the next. So why on Earth wouldn't they want to listen to both at the same time?

This is where Babymetal come in. Babymetal are three teenage girls, "Su-metal", "Yuimetal" and "Moametal", who have been blessed by The Fox God with the mission of saving heavy metal and uniting the world. Or, if you happen to be a Fox God sceptic, their manager and producer Key "Kobametal" Kobayashi has manufactured Babymetal, masterminding their radical fusion of heavy metal and Japanese idol pop. All this makes certain uptight metal purists very angry indeed, which I personally find incredibly funny. If you can bring yourself to award him an click, check out the anti-Babymetal rant by YouTuber Billy Kasper and marvel at how this big, whining cry-baby is practically brought to tears by the mere existence of these allegedly undeserving and talentless upstarts who haven't paid their dues and have the gall to sing in a foreign language he doesn't understand.

Kasper represents the small but vocal, largely internet-based minority of metallers who harbour ridiculous "tru-kvlt" attitudes and whose killjoy seriousness makes them look like silly wazzocks. Metal might be the last remaining tribe in terms of uniform and dedication to the scene, and nowhere is that clearer than at Download Festival, but the tension between "mainstream" pop music and "outsider" metal is one that is becoming increasingly irrelevant and has long been ambiguous anyway. There are plenty of older instances of metal colliding with pop in an entertainingly incongruous fashion, such as Andrew WK's brand of self-help ABBAcore or Lordi's triumph at the 2006 Eurovision Song Contest. Some people got angry about those matters too but are there really many metallers who listen to heavy stuff exclusively and genuinely despise other genres, especially pop? Deftones love Sade so much they've covered her. Anthrax's Scott Ian digs Madonna. As tQ editor John Doran has assured me, "In real life you only ever meet metalheads who have got a lot of time for R&B and hip hop and pop and stuff like that - these whining true cult whoppers who hate pop culture only exist on the internet in my experience" and he must know what he's talking about because until fairly recently he resembled someone disinterred from a Bronze Age burial mound.

Questions have been asked but the metal press has been generally accommodating of Babymetal (they've featured on the covers of Metal Hammer and Rock Sound) and established metal bands have also lent their support. Rob Zombie, for example, defended Babymetal against his own irate fans in hilarious fashion. Even Gene Simmons likes Babymetal (or has at least been pictured with them) and he is an antiquated dinosaur who usually can't fathom concepts as straightforward and graspable as rap music or clinical depression. You wouldn't want to be more narrow-minded than Simmons now would you?

At Donington Park, I fail to find any metalheads who are especially upset or angry about the presence of Babymetal on the Download Festival bill. Such scoffers are probably busy at home on the internet posting abusive comments under articles by exceptional metal writers such as Kim Kelly. In their absence is a fieldful of joyous moshers who don't seem too bothered by the delayed start. Five minutes before Babymetal are due to perform the heavens open as God punishes us for worshipping the devil's music by unleashing a downpour of such rainforest proportions that each massive droplet falls heavier than a Tony Iommi drop-d tuned axe riff. The stage crew wrap amplifiers in sheets of protective plastic and do their best to sweep huge puddles of water off the stage. By the time Babymetal's 40-minute set is over, we'll all be wet through to our pants with no regrets whatsoever.

The enthusiasm of the performers couldn't be more infectious. Grinning and gurning at the back of the stage, the face-painted players of the Kami band blast out sonic onslaughts of Slayer proportions. To give them their moment in the spotlight, the three singers occasionally depart the stage to allow the musicians to showcase their undeniable talents with virtuoso jams and solo spots that confirm exactly how gifted they all are without spiralling into the tiresome onanism that blemishes many a stadium metal act. Their expressions suggest that neither the Kami Band nor Babymetal's singers can believe their luck that this unique mash-up of thrash and J-pop is being lapped up with such fervour by metal crowds around the world. Su-, Yui- and Moa-metal look like they're having the absolute time of their lives, even under the physical stress of having to sing at pace while running through their intensely powerful dance routines.

"Choreography?" I hear the internet pedants type, "There's no place in metal for choreography!" To which I reply, fiddlesticks sirs! Firstly, metal is chock-full of choreography anyway. Don't tell me Deftones' Chino Moreno has never practised his graceful hand movements and sultry hip wiggles in his bedroom mirror. If Rammstein didn't meticulously rehearse where to move when, they'd end up fried to ashes by one of their many displays of phallic pyrotechnics. Secondly, Babymetal's choreography makes a refreshing change from all the rockers on the bill whose signature clichéd body pose is to rest one foot on a stage monitor as if to say, "Worship my big and bulging trouser-baubles, you adoring slaves". (In addition, no member of Babymetal addresses their audience as "motherfuckers" which is something a number of the other acts on this bill would be advised to take on board.) Thirdly, there is a heavy American wrestling presence at this festival. There's a ring in a tent where conventionally attractive muscular superstars pretend to fight one another in prearranged routines, and Megadeth's Dave Mustaine presents a Spirit Of Lemmy Award to a frowning man with grapefruit-sized biceps called Triple H. And we all know that wrestling's just ballet for beefcakes.

Despite the atrocious weather Babymetal draw a wide range of positive responses from the huge Download crowd. To my left, there is a bloke who looks like a cross between Lars Ulrich, Timmy Mallet and Iron Maiden's mascot Eddie who is giggling his way through the entire set from behind his oversized Wacaday shades as if being tickled by Durga herself. To my right, two lads are headbanging with deferential sincerity to the meaty music. Others whoop, pogo, raise their devil's (or Fox God's) horns or copy Babymetal's complicated dance moves as best they can.

"I wanna see a circle pit!" shouts Su-Metal, "Circle! Bigger! Bigger!" Sure enough, the crowd opens up and the result is the jolliest blooming circle pit I have ever witnessed in my entire life. While many pits can be violent and aggressive affairs full of topless men shoving, barging and colliding around chaotically, this one features a bunch of people simply running around in a big circle, lifting their knees high into the air like they're cartoon characters and sporting wide grins more beamy than the ceiling of a 17th-century farmhouse.

Everyone I speak to afterwards adored the Babymetal spectacle and agrees that the band can rock out like the best of them, even if some aren't won over completely. One attendee tells me that Babymetal "have riffs that Rammstein would be proud of" but their "Alvin & The Chipmunks vocals" are likely to prevent him from listening to them at home. I am inclined to agree until it dawns on me that I own several albums by the acclaimed Japanese noise-rock group Melt Banana, whose wildly yelping singer Yasuko Onuki isn't exactly the lowest-pitched vocalist in the world.

Parenthetically, Babymetal's set isn't the only marvellous meeting of metal and pop at this year's Download Fest. The one and only Kim Wilde makes a surprise guest appearance during the set of none other than Ravenshead anarcho grindcore pranksters Lawnmower Deth. She receives nothing short of a hero's welcome from the crowd who sing rapturously along to every word of the frantic punk-rock rendition of 'Kids In America'. To Wilde's immense credit, she also knows all the lyrics to both 'Egg Sandwich' and 'Watch Out Grandma Here Comes A Lawnmower'.

After three days of being blissfully, if muddily, isolated from news of the outside world, on the journey home the car radio informs me that some unhinged sad case has massacred 50 innocent people in a club in Orlando, hooligans have been beating seven shades of soccer shit out of each other in the streets and stadiums of France and the EU referendum debate has rolled into its umpteenth week of toxic anti-Other rhetoric. Maybe it's possible to find some solace in the bigger and longer picture, as Cannadine does. Muslims and Christians, Catholics and Protestants, Westerners and Easterners, men and women, metalheads and teeny-boppers... when it comes down to it are we really all that different? Can't we all chill out, stop taking our falsely-constructed differences and meaningless allegiances so seriously and just allow Babymetal to unite the world as The Fox God requests? At the rate their crowds have been expanding year upon year, perhaps Babymetal will soon succeed. I for one see little sense in resisting.