Mazda MX-5 Karuizawa Roadster meet

Summer in Japan's big cities can be hot and humid. Almost cloying. But up in the hills around Karuizawa, not far from where the 1998 Nagano Olympics took place, there's a light breeze blowing down from the mountain tops.

And on those gentle, cooling winds float the sounds of two thousand excited car enthusiasts, who have descended on the exclusive, breathtakingly pristine alpine destination to celebrate all things MX-5.

At the world's largest gathering of MX-5s, dubbed the 2016 Karuizawa Roadster Meet, I'm expecting to see several hundred vehicles... but the sea of Mazda convertibles lined up impeccably across three giant parking lots is jaw-dropping.

Completely agog, I'm paralysed by choice as we roll past rows and rows of rear-drive sports cars... where do I start?!

Instinct kicks in, and I plunge into the ocean of cars like a Blue-footed Booby diving for fish, inspecting one after the other, a laconic grin on my face. I take photos, waving to all and sundry – and incanting my best "ohayo gozaimasu" elicits delight from the locals.

Everyone's incredibly polite and friendly and I begin to feel like part of the gang. It also helps that I've rocked up in a brand new, fourth-generation (ND) Mazda MX-5.

The main attraction at the world's largest Mazda MX-5 jamboree is certainly the more than 1300 MX-5s on display, almost all of which have been customised – many with a level of creativity that'd make Leonardo da Vinci blush. There's even a couple of ultra-rare NB coupes.

But there's plenty more to see and do besides, starting with more MX-5 merchandise than you can shake a Mazda-branded selfie stick at.

Custom body parts, key rings, exhaust headers, carbon-fibre mirrors and a rather large array of plush leather seats are all up for grabs. Components for all four generations of MX-5 are available, from the original NA model that broke cover in 1989, through to the NB, NC, and up to the current ND model.

Oh and before I go on, here's the MX-5 count for the event:
NA (1st-gen) 555
NB (2nd-gen) 324
NC (3rd-gen) 237
ND (4th-gen) 247

Total MX-5 numbers – 1363
Total people attending – 2360

I spot a massive queue in the distance, investigate, and it turns out owners and enthusiasts are lining up to sign the one-millionth MX-5, which makes me grin for reasons you'll discover in another Japanese story...

The one-millionth MX-5 marks a milestone in more ways than one, setting a new Guinness World Record for the most popular two-seat sports car in the world. Way to go Mazda, yo! Okay that wasn't my best rhyme...

After a brief lunch of rice, chicken and a quail's egg served in a clay pot (which tastes absurdly good, although a Chico roll would've done), we check out some more merchandise, including a customised micro MX-5 powered by a two-stroke engine, complete with tailor-made carbon fibre parts, a race seat and even disc brakes.

These guys are passionate!

Next it's interview time and I meet a bloke, Masatoshi, with a black first-gen MX-5, featuring in the video. It's a ripper, fitted with Toda engine parts to hike the displacement from 1.8 to 1.9-litres (by increased cylinder bore). It's loud and fast, and like many of the MX-5 die-hards, Masatoshi has fabricated half of the body parts himself, including a rear wing big enough to dry your laundry on.

I also meet Ken, part of an MX-5 community who regularly meet, and Yuuki, whose yellow and black car was inspired by Eve, a sexy manga character. Yuuki calls her "erotic" and wants to marry her.

Mingling with the crowds is an entertaining experience – for all parties – and even with the language barrier it's clear everyone in attendance has a huge amount of passion for the 27-year-old two-seat convertible.

Then the covers come off the MX-5 RF, or retractable fastback, and the tightly-packed crowd goes bonkers.

It's only the second time the car has been seen, after its global premiere at the 2016 New York motor show, and watching the RF make its Japanese debut among the MX-5 faithful is quite a spectacle.

Oh, and it's the only MX-5 RF in existence in the world at present, a fact that isn't lost on the crowd.

Suddenly there's more yelling and three toddlers are attempting to be the fastest MX-5 junior driver. I ask for a go but get politely rebuffed... Next time, surely?

I have a short chat with one the coolest blokes at the event, Nobuhiro Yamamoto, who not only oversaw development of the current MX-5 but also helped design rotary engines in the past, including that of the 787B race car that won the 24 hours of Le Mans.

He's a mega petrol-head and says he loves checking out all the crazy modifications enthusiasts make.

"They call these cars "my roadster" and it's really enjoyable to see how customers are personalising their MX-5s," says Yamamoto, noting that some of the ideas he sees even make their way into production vehicles.

"I find a lot of interesting ideas to incorporate, small ones, I get a lot of stimulation looking at these ideas, how they change the models for their taste."

After spending a day meandering around the world's largest MX-5 gathering in Karuizawa, it's manifestly clear that car enthusiasts share the same passion, no matter where they come from.

But even when the event officially comes to a close at 3.00pm, the fun doesn't end... Perish the thought.

The roads in and out of Karuizawa are some of the smoothest, twistiest, most picturesque I've ever witnessed anywhere in the world. They're simply stunning, almost tailor-made for a compact, rear-drive car and it seems everyone – quite literally hundreds of MX-5's – have the top down for the cruise home.

The weather's perfect, the day unforgettable and methinks flogging a fresh ND roadster down the length of these epic mountain roads with hundreds of other mad-keen MX-5 fans is going to be an edifying experience… and indeed it was.