“Friendship is something everyone needs in life,” says Ms Keiko Matsumoto as she fries a pan of deer meat. “For me, it’s about being around people I can be myself with, whom I can have fun with without having to make any effort. It’s a little different from people at work, you know?”

She and her husband, Mr Keiji Matsumoto, and their friend Mr Kunihiro Tsujii have been camping together for about four years. MR PORTER has come to meet them at Suigen no Mori, a camping range deep in Yamanashi, the rural prefecture 60 miles west of Tokyo that is home to Mount Fuji.

Suigen no Mori is one of Japan’s more fashionable camping grounds. Archive issues of Popeye magazine decorate the tastefully lit reception area, where you can also buy the latest tools and outdoor equipment from Snow Peak. Individual camping sites sit at various levels around the grounds and large cedarwood bridges extend above the Doshi river that borders the site.

The trio sit around a campfire on the riverside, the gentle sizzling of the pan meshing with the cicadas trilling from the tops of the trees and the burble of the nearby river. The air is fresh but warm, still clinging on to the last vestiges of summer humidity. “Oishii [Delicious]!” says Keiji as he takes the first bite.

From snow-blanched mountains to tropical beaches, the Japanese archipelago features some of the most diverse topography in the world, which makes it ideal for outdoor pursuits. It is perhaps the country’s rich and verdant forests, however, that are most notable. Despite Japan’s penchant for industry, 67 per cent of its land is covered by forest and it’s there that many of the country’s residents – Tsujii, Keiko and Keiji included – go to pitch a tent and enjoy the fresh air.

Camping is the source of the trio’s friendship, but it has also helped Keiji and Keiko’s marriage. “We used to fight a lot, but somehow, when we started camping, all the fighting just stopped,” says Keiji. “I think one of the reasons is that we could relax. Communication is important when you’re camping. When I talk with other people who have the same interests or something in common, my stress goes away and her stress goes away. We’re happier.”

“I love being able to cook for everyone while we’re camping,” says Keiko. As well as the deer meat, she also prepares a preposterously well-made feast of katsuo tataki (seared tuna) garnished with raw sliced garlic and shredded shiso, beef steak with sea salt and a traditional Japanese recipe of tamago kake gohan (raw egg mixed with rice). Cold baked beans out of a tin this is not.

When Keiko isn’t cooking in the great outdoors, she works as a computer product developer. “Camping is so completely different from what I do in the week, but I find that being outdoors also helps me come up with better ideas for work,” she says. “I feel like time passes more slowly out here. When I’m working, it flows really fast, but if we’re outdoors it’s calmer, somehow slowed down.”

Keiji works in sales for a Japanese smartphone company. Tall and charismatic, he has bright eyes and an easy way about him. “Getting to meet and talk with people is the thing I love most about the outdoors,” he says. He calls camping his “takaramono” (literally: treasured thing). “Drinking together, talking together, it’s great. I learn so much just by talking with people.”

The couple met through work and have been camping together for about 14 years. “We started by renting some stuff and we really enjoyed it, so we bought some proper gear,” says Keiko. “And since then, we’ve been most weeks.”

“Actually, we spend about 111 days a year camping,” says Keiji. “It’s usually Friday, Saturday, Sunday. Every week.”

They became friends with Tsujii after meeting him at an annual hanami (cherry blossom viewing party) with the wider camping community in Tokyo. Keiji says that, although he doesn’t consider himself a core part of the camping scene in Japan – “I still like to have my independence” – the couple really hit it off with Tsujii. They go drinking together in Sangenjaya and Nakameguro and will often catch each other at their local convenience store. “I’ll see them in there sometimes and just laugh,” says Tsujii. “Normally it’s not the kind of thing that happens in a city as big as Tokyo, but I bump into them all the time. Maybe it’s fate.”

Helping each other pitch the tents, passing cooking utensils and unpacking camping chairs, it’s clear they’re all in sync and instinctively know what to do next. “Tsujii knows so much about camping and we all have different experiences we can share, so we can all teach each other things,” says Keiji. “And besides that, he knows what’s fashionable, so I’m always asking him what he thinks when I buy something new.”

Tsujii got into camping eight years ago after becoming fascinated by camping tools. “This older guy I knew had this really cool gas-powered outdoor coffee maker and I just thought it was amazing,” he says. Camping in Japan has soared in popularity over recent years and there are now magazines devoted to it. Their pages are packed with product recommendations, which means Tsujii is never short of new gadgets to try. “I like things that are a little strange,” he says. He shows off a drinking cup that can flatten and a silicone lighter case that keeps the flame from burning your hand when you turn the lighter upside down.

He does PR for various outdoor brands in Japan and so, for him, there’s little differentiation between work and leisure. That’s how he likes it. “My work doesn’t feel like work at all,” he says. “What I enjoy in my personal life is simply reflected in what I do as a job. Camping, cycling, mountain climbing, paddle boarding – it’s just what I do for fun.”

The survivalist element of camping has given Tsujii a sense of worth and independence, and handling Japan’s typhoons and extreme weather by himself has bolstered his confidence. “It’s good to feel that I’m looking after myself,” he says.

It has helped him make friends, too. His outdoor clothes and gadgets, he says, are a quick and easy way to signal his interests to others. “It’s a way I can introduce myself without having to say anything,” he says. “It kind of functions as an icebreaker. If I take my favourite tent with me when I go camping, it’s a way to start talking with other people.”

He also paints with acrylic, sketching faces onto stone. “He’s like the Van Gogh of the outdoors,” says Keiji.

Something all three friends agree on is how incredible and diverse the natural landscape is. “Nothing beats being up a mountain in a tent and waking up in the morning and looking out,” says Keiji, motioning unzipping the tent. “It’s just like, ‘Wow’!”

To fully appreciate what the country has to offer, he says, there is no better way than camping. “There’s a lot to discover here,” he says. “Everywhere in Japan offers a different view, different foods, different culture. To properly understand or feel it, you have to go and see it for yourself.”