Mystical moments: This is Japan but not as you know it

We've been walking in forest for hours but in a deep dark spot beyond the torii gate that marks the entrance to the sacred outer grounds of Usa Jingu shrine, the atmosphere suddenly changes. Moss has all but covered the crumbling remains of stone walls and there's a palpable energy in the air, as though the monks who gathered here centuries ago are still here somehow, maybe in some parallel universe.

I feel a bit weird asking my guide Andrew, on the quiet, if he feels something, too, but - to my surprise - without any hesitation he agrees. "The first time I came here I found it very unnerving but in a positive way," he says. "You feel an energy of deep history here. There's actually a lot of places on the track that have this vibe."

We're on the Kunisaki Long Trail, a route around the Kunisaki Peninsula on Japan's southern-most main island of Kyushu. The route links paths used by monks with others that simply offer mighty fine walking of the scenic and cultural variety. It's about 150 kilometres long in total and we're tackling 70 kilometres of highlights on Walk Japan's 10-day Kunisaki Trek.

Between the 9th and 12th centuries, about 800 monks were drawn to the solitude and ascetic promise offered by a peninsula largely isolated thanks to jagged mountains and difficult terrain - from above, the peninsula's risen volcanic heart, radiating ridges and ravines all the way to the coast, is clear. When local feudal lords and their samurai rose in power about 800 years ago, leading to civil war, the spiritual heyday came to an end, leaving a region crammed with peaceful temples and shrines.

It takes another hour of hiking to reach Usa Jingu proper, a vast and impressive complex of vermillion torii gates, shrines, and placid ponds linked by pathways and stone steps. With a history spanning 1300 years, it's one of Japan's most important shrines and is notable for being the starting point of a syncretic worship combining native Shintoism and Buddhism (introduced from China).

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Considering the world at large, two religions cohabiting peacefully seems surprising, but in Japan - Kyushu, especially - the sight of Buddhist temples cosying up alongside Shinto shrines is common. "Japanese don't identify as a particular religion," explains Andrew. "It's kind of life and death, instead. Shinto is practised for things like marriage and births, Buddhism for funeral rites."

Usa Jingu is by far the biggest and grandest place of worship we encounter but there's a different satisfaction in discovering countless other shrines and temples tucked into cliffs or overrun with moss in thick forests, where the only way to reach them is to hike steep hills and navigate precipitous ridges, just as monks once did.

Those monks weren't really seeking an easy ride - suffering took them closer to nirvana - and our trail regularly drizzles atop ridges at times so narrow that I feel like I'm walking the plank. Bolted chains help us negotiate particularly steep sections (sometimes, near vertical), thankfully always short and conveniently studded with rock-nub footholds.

It's not for the faint-hearted but what we give in sweat and quivering muscles, we gain in incredible panoramas. Snack breaks are shared with small Buddhas perched on mountain tops that showcase rocky ridges and spires protruding above the canopy far into the distance. Autumn daubs red and orange among the green.

Down lower, walking among the forests is equally wondrous. Some are peppered with boulders and so vibrant with moss and layered greenery they seem to change the light. Shrines back themselves into concave cliffs dripping with vines, and in hidden caves we discover stone carvings.

It's not all wild walking though. In a welcome contrast, our route also takes us through quaint villages surrounded by rice paddies that have existed for a thousand years or more, where front yards sprout trees with branches manicured into "clouds" - the result of Niwaki pruning - and tufts of leafy greens form neat rows in vegetable gardens. Heavily laden persimmon trees are everywhere, and two old ladies fill our cupped palms with fruit.

It's picturesque and peaceful though, at times, the sleepy vibe borders on ghost-town-like. Japan's declining rural population has left more than eight million houses across the country abandoned as the young move to cities for work, and we pass many buildings reclaimed by nature along with scattered life-sized stuffed mannequins of "villagers", made by locals to create a sense of community.

In an effort to breathe life back into the region, Walk Japan have based two offices here, bringing a vibrant team of about 30 to Kunisaki, plus their Community Project invests in such efforts as property renovation, tending parks, replanting woodland, and helping the elderly to maintain their farms and stay in their homes.

Eighty-year old shiitake mushroom farmer Etchan is one such beneficiary and she's full of smiles as she hosts us for morning tea and mandarins. Later, another villager provides us with lunch. The warmth and respect shared between these women and our guide is something resembling family.

Times might have changed but there's no hiding Kunisaki's heart and soul, nor its history. Even in small villages, torii gates can be found standing in the middle of farmers' fields, and stone Buddhas hide among overgrown roadside foliage. In walking here, we've immersed ourselves in a part of the country that very few tourists get to visit and explore. We've breathed in its spiritual energy and sat with its people. We've made our own pilgrimage and perhaps a little piece of us will stay on the land too, just like the monks of the past.

Getting there: Qantas and Japan Airlines fly from most Australian capital cities to Fukuoka on Kyushu from where you can catch the Sonic Express train to Nakatsu, the tour's starting point.

The walk: Walk Japan's 10-day guided Kunisaki Trek costs JPY480,000 ($4909) and includes accommodation, entrance fees, luggage transfers and most meals. Shorter, easier and self-guided options are also available.

Explore more: walkjapan.com

The writer travelled as a guest of Walk Japan.

Pictures: Laura Waters; Walk Japan