TOKYO - A wintry honeymoon nearly turned deadly for Singaporean Amelda Lim, 28, and her Malaysian husband Long Ji Yung, 27, after they were stranded on Hokkaido's tallest peak on Tuesday (Oct 17).

But their survival smarts and acquaintance with elderly Japanese couple Masahiko Kato, 71, and his wife Yumiko, 65, led to their being found conscious nearly 22 chilly hours after their first distress call on the 2,291m-tall Asahidake.

Overcome with fatigue and as nightfall and low visibility rendered evacuations by air difficult, the four spent Wednesday night up on the mountain under the watch of emergency rescuers, who provided them thermal insulation and tents.

They were airlifted by helicopter at 6.10am on Thursday (5.10am Singapore time), to the nearby Asahikawa Medical University Hospital for a health check-up.

Mr Long and Ms Lim, who are now recuperating, have not responded to a Straits Times request for an interview.

According to their LinkedIn profiles, Mr Long is an accounts executive at travel agency JTB Singapore, while Ms Lim works as a senior designer at the Siren Design Group.

Ms Lim's colleague, who declined to be named, told The Straits Times: "She is fine. Amelda has updated us via WhatsApp that she is recuperating in hospital."

When asked about Ms Lim's condition, the colleague added that it was "definitely not critical".

​Mr Long's colleagues at JTB Singapore also confirmed to The Straits Times that he is on a honeymoon in Japan, and that he is in hospital.

The newlyweds, together with Mr and Mrs Kato from Yokohama, were found near a water source some 1.5km south-east of Asahidake's ropeway station at about 1,600m above sea level, after rescuers spotted a headlamp amid heavy snow.

"All of us are alive," Mr Kato, who works in hospital management, shouted out to cheers from the team of emergency rescuers.

The four had survived a day with barely any food and without a tent amid temperatures as low as minus 7 deg C. Snow cover at the area they were discovered was between 30 centimetres and 40 centimetres, reported Hokkaido Shimbun.

The leader of Hokkaido police headquarters Kazutaka Nishimura told NHK: "The four took cover in a mortar-bowl shaped structure that was sheltered from the wind, and waited there.

"As they kept still without moving, they did not wear out their physical strength and I believe this is what led to their survival."

A member of the Ground Self-Defence Force who was involved in the search operation added: "The 'feels like' temperature in the vicinity was minus 20 deg C, with extremely low visibility. Given the harsh environment, we are extremely thankful that the four were found safe and sound."

An unseasonal cold front has led to lower temperatures throughout Japan this week. According to the Sapporo District Meteorological Observatory, such temperatures on Asahidake would only have been typical in mid-to-late November.

The mountain towers over a hot springs resort of the same name in Higashikawa town in central Hokkaido.

Mr Long and Ms Lim had met the Japanese couple while on the mountain, with the four taking a wrong turn near its seventh station and soon finding themselves stranded.

Mr Kato made the first call to police at about 7.35pm on Tuesday. Both he and Ms Lim made separate calls to the police after 8am on Wednesday, reporting that all four were conscious and alive, although Mr Long was showing symptoms of hypothermia.

The Hokkaido Shimbun reported that Mr Long was stretchered into hospital upon arrival, while the other three could "walk in with a steady gait".