By day, Naoko Watanabe works as a nurse. In her spare time, she ventures into the "death zone," where oxygen levels fall to about one-third of those at sea level.Two years ago, the 44-year-old became the first Japanese woman to climb all 14 of the world's mountains above 8,000 meters.The achievement came only after a number of setbacks and close calls.On her first attempt to climb Mt. Everest in 2011, Watanabe turned back just 150 meters from the summit because of bad weather. On other climbs, she slipped and fell as oxygen deprivation clouded her consciousness and survived an avalanche on …READ FULL ARTICLE