The Vietnamese were working as interns at the Aioigumi Joint Stock Company on the island’s Miyazaki Prefecture, the Vietnamese embassy in Japan said on Monday night.

Fearing their accommodation might be unsafe when the typhoon made landfall, their Japanese director had invited them to his house, which doubled up as the firm’s office.

The duo and the director’s wife and child have been missing since Sunday after their house was hit by a landslide. The director was injured and is in hospital.

Haishen, one of the strongest storms to hit Japan this year, left at least two people dead besides the four missing people and 108 injured.

The storm battered almost the whole of the main southwestern island of Kyushu with strong winds, causing massive blackouts and disrupting transportation, the Japan Times reported.

Vietnamese, numbering almost 412,000 last year, are the third largest group in Japan after Chinese and South Koreans, according to Japan's Justice Ministry.