TOKYO: At least four people died and five were reported missing after a new spell of torrential rain unleashed floods and landslides in Japan overnight, police said Saturday.

The weekend tragedy came after a series of landslides and floods earlier this week killed 15 people.

Torrential rain hit Japan's southern main island of Kyushu Friday, causing mudslides and floods and killing four people.

A 73-year-old man was found dead after a mudslide struck his home late Friday in Fukuoka prefecture, located in Kyushu, a police official said.

"I heard a roar like a thunderbolt... It was overwhelming and scared me a lot," a neighbour told a private television network as he recalled the moment the landslide hit the area.

A 54-year-old woman was found dead after her car was swept into an irrigation channel, while a 60-year-old man died after falling in a street ditch, the Fukuoka police said.

A 67-year-old man also died in the southern prefecture of Nagasaki, local police said.

"His wife found him under mud and a fallen concrete fence" outside of their home in Iki City in the prefecture Friday, a police official said.

The rainfall in the city hit 108 millimetres (4.32 inches) an hour Friday afternoon.

Five people were missing in southern and western Japan.

A 61-year-old woman and her 34-year-old daughter were feared to be buried under mud after their home was hit by a landslide in Fukuoka prefecture.

"The home was completely buried under mud. We are trying to get rid of the mud and rubble as the two can be underneath," a Fukuoka police official said.

Another woman has been reported to be missing by her husband but police were unsure whether the case was linked to the torrential rain, the official added.

Two people were missing in western Japan's Hiroshima prefecture after a landslide.