At first glance, Naoshima, a teeny five-square-mile island in Japan’s Seto Inland Sea, doesn’t look like much. Just a quietly unassuming, albeit perfectly pretty rural outpost – a sparing landscape of green mottled cliffs and empty, biscuit-coloured beaches. Then you notice the giant pumpkins. There’s the big yellow one covered in black polka dots at the pier.

Then the even larger, red-spotted pumpkin greeting visitors at Miyanoura Port. Later, strolling between villages along hushed island roads, I’ll spot more bizarre objects -some stuck in the sand, others peeping out from bushes – a huge tea cup, a geometric fishing net I can’t resist climbing inside for a picture, a multicoloured camel with trees growing out of its humps.

What do you think of when you hear ‘Japan’? Blade Runner-style cityscapes, strewn with video megascreens and neon? Robot waiters and cat cafes? Or maybe tranquil temples, and sacred misty mountain tops. Certainly Japan’s ‘Golden Triangle’ – your typical tour that takes in Tokyo, Kyoto and the Japan Alps – can deliver. But, keen to see another side to this famously reserved, futuristic island nation, I’ve scooted further south along the country’s main island of Honshu, where there’s a whole other Japan waiting in the wings to be discovered; an ‘alternative Golden Triangle’, which topples as many stereotypes as it confirms.

Which is how I come to be on Naoshima. Once a sleepy fishing island, idle in its anonymity 700km below Tokyo, Naoshima is today completely overrun by contemporary art. Part-theme park, part-playground, and all brilliant, wherever you turn here, you’ll bump into an installation, a sculpture, or ultramodern, avant-garde museum. And those psychedelic pumpkins? They’re works by Japan’s greatest living artist: the eccentric, red-wigged octogenarian Yayoi Kusama, who has lived in a psychiatric hospital since 1975, and was an early influence on Andy Warhol. True story.

It’s a concept with just the right balance of crazy and genius to be distinctly Japanese, while offering a very different experience to your noisy megalopolis or reflective Zen garden. Even that most staid of institutions, the museum, is made thoughtfully radical: at Chichu Art Museum, I descend into an ethereal, all-white underground chamber, sparsely decorated with Monets. (Chichu literally translates as ‘in the earth’.) The white-out brings out the becalming effect of the Water Lilies; the silent museum staff are also dressed in head-to-toe white, and as they glide around, I’m left with the distinct impression that I’ve dropped through a portal into a museum from the year 2135.