At dawn, the veteran adventurer wakes after a night in a private low-oxygen chamber. He straps weights onto his ankles, hoists a 44-pound backpack onto his shoulders and hikes for hours around Tokyo. Sometimes he adds a stroll on his treadmill.
Ask Miura why he isn't on the golf course or puttering around a vegetable garden, and he has a simple answer - Mount Everest.
Miura is one of Japan's old men of the mountain, a small cluster of graying Japanese climbers who since 2002 have been passing among themselves an august title: the oldest person to have conquered the world's tallest peak.
"It's a tough but wonderful thing to get to the peak when you are past 70," Miura said at his Tokyo home. "I hope to send the message that we have the potential for many things in this aging society."
Miura is already famous for having skied down Everest in 1970, a feat captured in an Oscar-winning documentary. Now, for seniors like him, climbing the 29,035-foot Himalayan peak is as extreme an elderly activity as they come.
It's no wonder that the Japanese have cornered the market in elderly Everest conquerers. The country has the world's longest-living population and is going through a boom in activities for the elderly.
Toshio Yamamoto started the string of Japanese victories by scaling the peak in 2000 at 63 years. In 2001, American Sherman Bull reached the summit at 64 years old. Tomiyasu Ishikawa, then 65, took the title in 2002.
Miura won the distinction in 2003, at 70, but was eclipsed by fellow Japanese climber Takao Arayama, who scaled the peak in 2006, just three days older than Miura was when he did it. Katsusuke Yanagisawa took the crown this year, at age 71 years and 63 days.
Now Miura wants to reach the top again.
"It feels like the goddess of Everest is beckoning me to come back," said Miura, who is planning an assault on the mountain next spring, when he'll be 75 (Edmund Hillary was 33 when he became the first man to climb Everest, in 1953). None of three other Japanese record-holders plans to scale the mountain, they say.
The Japanese also hold the record for oldest woman on Everest: Tamae Watanabe in 2002, at age 63.
Some attribute the prevalence of Japanese adventurers among the ranks of older climbers to the same factors that make them live increasingly longer: a diet heavy in vegetables and fish, excellent health care, and trim physiques.
"Overall, the elderly have more vitality than before and their performance in sports is also improving," said Takuji Shirasawa, a specialist on aging at the Tokyo Metropolitan Institute of Gerontology who consults Miura.
Another factor in play is increasing affluence.
The spread of commercial expeditions beginning in the early 1990's allowed inexperienced but rich climbers to reach the summit.
Arayama, who broke Miura's record when he scaled the peak in 2006, said climbing Everest was a remote idea in his 20s, when the science was undeveloped and the experience was not widely open to the general public.
"The way we climb has changed. You use oxygen so you won't tire yourself, and more was found out about the best pace of climbing, and that's why I got to climb," he said.
Money brings world-class equipment, expert assistance on the mountain, and state-of-the-art training.
Miura's climb is estimated to cost around $1.7 million spanning three years to 2008, including overseas training trips and $515,000 for the May expedition, which includes expenses for his climbing companions as well as communication and video recording costs. The effort is supported by corporate giants including Toyota Corp. and Toshiba Corp.
Miura has built a $260,000 low-oxygen room inside his Tokyo home to help him acclimatize to the thin air. A large-size photograph of Everest looms over his stationary bike machines and treadmill.
All that cash rubs some climbers the wrong way.
Miura relies on "his financial strength to make up for what he lacks," said Yutaka Nakagawa of the Japan Mountaineering Association. He said that sets Miura apart from world-class alpinists such as Italian Reinhold Messner.
"It bothers me that people equate Messner, who climbed without oxygen, with Miura, who spends money and uses just about everything," Nakagawa said.
None of this bothers Miura much.
He's in excellent shape. A test before his 2003 climb showed him with the fitness of a 39-year-old man, according to Masayoshi Yamamoto, exercise physiology professor at the National Institute of Fitness and Sports in Kanoya in southwestern Japan.
Staying active into old age is in his genes. His father made headlines three years ago when he skied down Mont Blanc at age of 99. He died last year at 101.
His son might not be the only senior at the summit. American climber Dick Bass may also try at age 78. Yanagisawa said he knows of at least one other Japanese climber in his late 70s who wants to scale Everest next year.
Miura isn't taking any chances. He has twice been treated in recent months for an irregular heartbeat. His son Gota will accompany him to Everest, as he did in 2003, and during the climb they will e-mail medical information such as his heart rates to doctors in Japan.
Miura says setting a record isn't all that important, since someone else will surely come along and break it. Instead, he said, "It's about discovering what I can do."