Mitsutaka Uchikoshi, 35, went missing for 24 days while going climbing with his friends at Mount Rokko, western Japan. He survived in cold weather without food and water by falling in to a state of "hibernation":
He had almost no pulse, his organs had been shut down and his body temperature dropped to 22C (71F) when he was found.
Medics say they are still puzzled how he survived because his metabolism was apparently almost at standstill.
Mr Uchikoshi is believed to have tripped and lost consciousness after leaving his party to descend from the mountain on his own.
"I lay down... in a grassy area, which felt good in the sunshine, and eventually I fell asleep," Mr Uchikoshi told reporters at a news conference at a hospital in Kobe, where he was treated.