And he is not finished with it. Despite coming close to death, firmly stating that "three times is enough" after his last record-breaking climb and undergoing yet more heart surgery for his cardiac arrhythmia (irregular heartbeat), Miura says he is in training to ski down Cho Oyu, the world's sixth-highest mountain, when he is 85 and plans to launch a fourth Everest bid when he is 90.

"I'm thinking of the next Everest expedition - if I'm still alive by then," he adds with a smile.

Born in 1932, Miura grew up during the tumult of the second world war and the fall of the Japanese empire. Raised amid the snowy peaks of Japan's northern Hokkaido prefecture, he is the son of Keizo Miura, a famed skiing teacher and adventurer who had become the oldest person to climb Mount Kilimanjaro, in Tanzania, at the age of 77. Following in his father's footsteps, Miura became a professional skier and was later the headmaster of a high school.

While his debut climb up Everest, in 2003, was at the time the record for the oldest person to reach the summit, it was far from his first major achievement. Miura is a household name in Japan, known as "the godfather of extreme skiing". His passion for snow sports predates his mountaineering, and in 1964 he set a world ski speed record: 172km/hour - granted, his record lasted only one day. (The current record, achieved last April by Italian Simone Origone, stands at 252.63km/h).

Miura skied down Japan's Mount Fuji in 1966 and Mount McKinley, the highest peak in North America, in 1967. He was then invited by New Zealand's tourism board to ski the Tasman Glacier, where he met his "superhero", Edmund Hillary, the first man to climb Everest, who inspired Miura to "be Everest" and "make history" for himself.

When he was 37, Miura became the first person to ski on Everest, descending 1,280 vertical metres from the South Col, on a gradient of 40 to 45 degrees, in less than two and a half minutes, with a drag parachute and fighter pilot's helmet for protection. The parachute was meant to act as a brake but, as he careered out of control, sliding down a sheet of sheer ice towards almost certain death on Khumbu Icefall, the chute failed to stop him. Just before the icefall, Miura flew off a rock and was propelled about 30 feet into the air before landing on a small patch of snow that - miraculously - broke his fall. He was only 250 feet from a deep fracture in the glacier.

His story was turned into the film , which in 1976 won the Oscar for best documentary. But his achievement was marred by tragedy: "Six of the sherpas around me died. It was tragic and terrifying."

Last April, an even more devastating tragedy struck Everest. A 7.8-magnitude earthquake hit Nepal, triggering a huge avalanche from Pumori and down into Base Camp. It was the deadliest disaster in the mountain's history, claiming 22 lives, closing the mountain for the season and adding to the sense that death and Everest go hand-in-hand.

Having witnessed the mortal danger of Everest up close, Miura says that the death of the sherpas in 1970 was hard to bear but that his determination to conquer the mountain was renewed.

"From that time I made the decision that one day I would come back and try to climb it."

It was 33 years before Miura did return. Teaching and a skiing career kept him occupied before a failed bid to enter politics in the mid-1990s. He ran unsuccessfully for both the governorship of Hokkaido and as an MP. He then, as described in his book , became "a fat old man" and entered into something of a mid-life crisis.

"I lost all motivation and didn't know what to do next," he explains. "In my 60s I got metabolic syndrome. I drank and ate too much and didn't do enough exercise. I had a diabetic problem, and had heart and kidney disease."

But he drew inspiration from his father, who was still skiing down Europe's Mont Blanc at the age of 99.

"I wanted to surprise everyone," he says.

The road back to Everest was lined with obstacles. In 2003, Miura had to overcome diabetes and weight problems, and by the 2008 expedition - aged 75 - his cardiac arrhythmia had begun to slow him down. After returning to Japan from Nepal, he had two heart operations and took a year out to rest.

"During the winter I stay in Sapporo, in northern Japan, and ski - that helps me train," he says. "However, I fell during a jump and smashed the right side of my pelvis, breaking five bones in total. It was a big accident and I had lots of surgery afterwards. Usually when a man aged 76 breaks that many bones, they will use a wheelchair for the rest of their life."

Doctors warned him he might never walk properly again. But only one year after the accident Miura began getting fit in his own unique way.

The balanced Japanese diet is credited with helping the nation to have the world's highest life expectancy: 85 years for men and more than 87 for women. Miura is a proponent of healthy eating and organic food. He starts every day with a breakfast consisting of cooked rice, fermented soya bean, miso soup, eggs and fish. Once a week he will treat himself to an 18 ounce steak.

The first stage of the physical training involved strapping 1kg weights to each leg and 10kg to his back and walking the 9km between Tokyo Station and his office - and back again - every day. He soon stepped this up to 5kg on each leg and 30kg on his back as he gradually regained the stamina required to survive nearly 9km into the sky.

The air at the mountain's so-called "death zone", above 8,000 metres, is dangerously thin, with only a third as much oxygen to breathe as at sea level. The extreme cold that can cause frostbite if any part of the body is exposed, and dangerously high winds, mean peak fitness levels - not to mention mental fortitude - are required to reach the summit. Scientists have estimated that the "physical body age" of a person under the stresses of being at 8,848 metres is 70 years on top of their actual age. By this reckoning, Miura would feel like a 150-year-old on the summit.

"In my office I have an altitude training room, where I can train up to the condition of 6,000 metres of elevation," he says. "Up to six months before the Everest mission, I would train three times a week in the low-oxygen room."

Miura suffered a major setback when he and his team went to the Himalayas six months before the expedition.

"In October 2012, I climbed Lobuche East [a 6,000-metre mountain in Nepal] but I got altitude disease, which triggered my cardiac arrhythmia. I had been planning to stay there for two months but gave up after two weeks and returned to Japan for another heart operation," he explains. "The operation was a success but, because of the imminent Everest expedition, I only gave myself a two-week period of rehabilitation."

Then illness struck: "Influenza was going around at that time and I got it bad, with a fever higher than 40 degrees [Celsius]. My heart stopped and I was carried to hospital to have an electric shock to get it going again."

Yet another heart operation followed as Miura, his team and his doctors tried to patch up his ailing body.

"This was all so close to when we were due to make the expedition," he says. "All the people around me thought that I would give up. But I never had any intention of giving up. On January 15, I had one final operation on my heart and I left Japan on March 20. I had no more time for rehabilitation."

Miura achieved his goal by adopting new tactics.

"On the walk from Lukla to Base Camp, I totally changed my style of trekking from the previous two expeditions," he says. "There is an old Japanese proverb that all people should only work for half the day. Usually when you make the climb, you wake up at 6am, have breakfast and trek for the whole day. This time I had to think about my heart condition, so I would eat breakfast, walk for half a day then have a good lunch. Then a one-hour nap, and then just enjoy the wonderful views around me with some tea and cake in the afternoon. I did this every day for two weeks on the way to Base Camp. This worked and we were all in very good shape. When we reached Base Camp, my heart was fine; my legs and whole body were in the best possible condition."

At Base Camp (5,364 metres), an expedition starts to get serious.

"From Base Camp, you have to start conditioning yourself for the summit, such as walking up to the Khumbu Icefall and up to Camp One and back. Then up to 7,000 metres and back," Miura says. "This time, I did a different type of training. The icefall would have been particularly dangerous at my age. Instead I went up Mount Pumori, at 7,100 metres, which is the other side of Base Camp. I did it twice and it was great preparation."

The team set out on the eight-day climb from Base Camp to the summit on May 16, many if not all of the others in the party amazed Miura had lasted so long. The first major climbing challenge is Khumbu Icefall, nicknamed the Ballroom of Death and Popcorn Field, and one of the most lethal sections of the most common South Col route to the summit. Jon Krakauer wrote in the award-winning book that "each trip through the icefall was a little like playing a round of Russian roulette".

The team were lucky: they had good climbing conditions. With clear blue skies overhead, they made the final push for the summit on the morning of May 23.

"The hard part was not the climb itself," Miura says. "When I reached the summit it all sank in. I could not believe it - I was standing there for about an hour. I took off my oxygen mask and just enjoyed the view. I was able to make phone calls and let everyone know that we had made it."

Miura's wife, Tomoko, had been waiting nervously for news with their daughter, Emiri, in Tokyo. Once the call came through, his wife replied, "I think it's best if you just come down quickly now."

Eighty per cent of the more than 250 deaths recorded on Everest happened during the descent.

"The Grim Reaper was telling me to give up," Miura says. "I had a really hard time as we started to go down. From around Hillary Step [88 metres from the summit] I was exhausted. My team helped me rope down very slowly, but I was shattered."

It was then that the weather set in and Miura became convinced he was going to die. If so, at least he would be "doing the thing I love the most".

"I would walk 10 paces and then need to stop, then another 10 and then stop. We inched down to around 8,500 metres, but that's when the snowstorm started and the weather worsened," he says. "The existence of Camp Five saved my life. Under the original plan, we were not intending to stop at Camp Five because it was not supposed to even be there any more - we thought the sherpas had cleared it away long ago. We stopped for an hour. We were able to boil water and eat 'Miura special cake' [a high-energy fruit and nut cake] and that break gave me the strength to carry on and go down to South Col."

When the team finally reached Advanced Base Camp, at 6,500 metres, they knew they were safe. Struggling with exhaustion and with the prospect of an increased avalanche risk lower down the mountain, Miura took a helicopter from the camp to Kathmandu - leading to a handful of "alpinists" reportedly questioning whether a climb can be "fully complete" if you don't walk all the way down the mountain, too. The team got back to the Nepalese capital and on to a hero's welcome in Tokyo. Once home Miura could think of "nothing but rest".

Now, however, he is focused on his next challenges. The first is to ski Cho Oyu in 2018. The dream to climb Everest at the age of 90, in 2022, may be a necessity to keep hold of the record. Miura's long-term rival, the 84-year-old Nepali climber Min Bahadur Sherchan, was forced to abandon his bid to reach the summit last year when the mountain was shut following the avalanche. In 2008, when Sherchan was 76, he became the oldest Everest climber (breaking Miura's earlier record). He tried to summit again in 2013, to better Miura weeks after the latter reclaimed the record, but had to abandon the climb and was airlifted off the mountain suffering chest problems. Miura says he wishes Sherchan well and that their rivalry has driven them both on to greater heights.

"I have had many illnesses and injuries, and while it would have been preferable not to have had them, I think it was good that I had to overcome hurdles before achieving my goal," Miura says. "I think if one regards the age of 80 as a start, his or her life will become more interesting.

"You need a target - however big or small - and to build your health and fitness towards it. It is not necessary to climb a mountain. It can be anything. I climbed Everest three times and each time experienced a health problem for elderly people. But I could cure them because I had a goal. That gave me motivation to fight and beat the illnesses and injuries. If there was no goal I'm sure I would still be bedridden or in a wheelchair after I broke my pelvis. But I had that goal to climb Mount Everest. I got fit and I got to the top."