Harwood, a slightly built computer systems analyst, survived for more than a week in the rugged California mountain range without any food.
When she shattered her leg trying to hike back to camp, she crawled for miles to a creek bed where she used a water filter to stave off certain death. And when rescuers drew close, she blew on a whistle until they found her.
Harwood's incredible survival story is a testament to her own ingenuity as she overcame injury and the elements to escape alive.
But it's also a triumph for rescuers, who battled adverse conditions including smoke from a nearby forest fire to find her just in the nick of time.
Harwood, an employee of the semi-conductor giant Intel, went missing during a seven-day Sierra Club backpacking trip in Kings Canyon National Park, about 160 km northeast of Fresno, according to Trey Pollard, a spokesman for the environmental organisation.
She somehow became separated from her group. When her fellow hikers couldn't find her, they called authorities, who launched a massive search for Harwood.
A total of 14 agencies pitched in to try to find the missing hiker. Fresno County Sheriff's deputies searched the remote stretch of the Sierra Nevadas on foot and horseback.
When that didn't work, they tried using search dogs, helicopters and even a drone.
But rescuers were stymied in their attempts to find her by a nearby wildfire, which blanketed the mountainous terrain in ash and smoke.
The Rough Fire, which has scorched nearly 160 sq km of California forest, came within 5km of rescue workers, according to Fresno County Sheriff lieutenant Rick Ko.
The bushfire was the least of Harwood's concerns, however.
"She was at about 10,000 feet altitude," Ko said. That elevation can cause altitude sickness and disorientation, he explained.
"The forest there is there dense and rocky. It's very treacherous terrain," he said.
"I've flown that area a number of times. It's amazing. It's beautiful. But walking there can be very, very dangerous."
In addition to the unforgiving terrain, Harwood had to overcome exposure to freezing cold nights and wild animals, including bears, mountain lions, coyotes and snakes, Ko said.
Harwood, a widow, went missing almost exactly a decade after the sudden death of her husband, Bret Michael Harwood.
It appears as if she took up hiking after his passing, occasionally posting photos from her hikes on social media.
She had recently moved from Orangevale to Folsom and didn't know anyone on her hiking expedition, a friend, Curtis Hendrickson, told the Sacramento Bee. But Harwood was used to hiking solo and was a "a very knowledgeable, experienced backpacker," he said.
"She's very resourceful," friend Debbie Janas told local TV station KCRA after Harwood first went missing. "So if anybody has a great shot, it's definitely Miyuki."
"Miyuki we miss you and love you and pray for your safe return!" co-worker Deana Switzer wrote on Facebook on August 26, commenting on one of Harwood's hiking photos.
"We know that you are a strong and capable woman and look forward in seeing you soon. God be with you my friend!"
Harwood's resourcefulness would be harshly tested, however. Harwood tried to make her way back to camp but fell on some rocks, shattering her leg, Ko said. It isn't clear when, exactly, she was injured.
Without food or water, Harwood had to drag herself several kilometres to a creek, where she used a bottle and filter to strain water to drink.
"It took her two days to get to that water source," Ko said. "But it probably saved her life."
As the horizon glowed an angry orange from the nearby bushfire, rescuers slowly closed in on Harwood's location. When she heard them approaching, Harwood summoned the strength to blow on a whistle, alerting them to her location.
Harwood was then airlifted by helicopter to a hospital where she underwent surgery on her broken leg.
She is in stable condition but has not yet spoken to media. Her family has asked for privacy as she recovers from her injuries.
"Miyuki desires, above all else, uninterrupted rest and quiet," the family said in a statement, according to AP.
But Harwood was in good spirits and grateful for her rescue, officials said on Monday.
"Her voice was strong," Fresno County sheriff Margaret Mims said, according to the Guardian. "She was extremely thankful that people were looking for her."
Harwood is not the first person to go missing recently in the Sierra Nevadas, a 112km-wide mountain range that runs 640km up the spine of California.
As officials searched for Harwood, they also came across the body of another woman who had disappeared earlier in the northern summer.
On August 23, authorities found the body of a woman believed to be Zillabel Jane Friesen, according to the Fresno Bee. The 81-year-old had been missing for just over a month.
Like Harwood, Friesen loved the outdoors and often went for long drives or hikes.
"[She] loved to go out and drive and be in nature," her daughter, Melaney Shaum, told the newspaper.
According to Ko, the Fresno Sheriff lieutenant, roughly half a dozen people go missing in the area every year. Although most are found alive, deaths are not uncommon.
Hikers often underestimate the harsh terrain and unpredictable weather, he said.
"It can snow in summertime up there," Ko said.
"We always hold out hope that we'll find people alive," he added. "We never write people off. We vigorously search for anyone who goes missing.
"Sometimes there is a reward like this," he said, "and sometimes it's tragic."
- Washington Post-Bloomberg
