The pair reportedly had been climbing the Hida Mountains on Honshu since last Friday, and called for help two days later when they were caught in severe weather.
Rescue teams deployed by the Nagano authorities were unable to reach them on Monday due to the conditions, according to reports.
Local media reported that a helicopter located the pair on Tuesday.
One of them, a 30-year-old man, is said to be conscious when he was airlifted to hospital.
But his companion, identified by Japanese media as a 22-year-old Hong Kong man living in Tokyo, was pronounced dead shortly after being found.
In response to media enquiries, the Immigration Department on Monday said it had contacted the Office of the Commissioner of the Ministry of Foreign Affairs in the SAR and the Chinese consulate-general in Nagoya after receiving requests for assistance.
The department added that it’s in close contact with the relevant authorities and will provide all possible assistance to the victims’ families.