Miyuki Hatoyama, 66, the charismatic wife of the leader of the incoming Democratic Party of Japan (DPJ), has also described how she met Tom Cruise in a former life and enjoys "eating" the sun for energy.
Writing in a book published last year, she said: "While my body was asleep, I think my soul rode on a triangular-shaped UFO and went to Venus. It was a very beautiful place and it was really green."
Her extra-terrestrial experiences ties in neatly with her husband Yukio Hatoyama's nickname "The Alien" which came about due to his large eyes.
Mr Hatoyama is due to be voted in as prime minister on September 16 after his party defeated the iron grip of the Liberal Democratic Party after more than five decades of near-interrupted power.
The party leader met his wife - a former musical actress who was born to Japanese parents in Shanghai - while he studying at Stanford in the United States.
Mrs Hatoyama, who is renowned for her healthy cooking having published several food-related books, described her UFO experience in a book called "Very Strange Things I've Encountered."
After waking up, Mrs Hatoyama wrote that her then husband dismissed the experience, claiming that it must have just been a dream.
However, referring to Japan's next prime minister, she wrote: "My current husband has a different way of thinking. He would surely say 'Oh that's great'." Earlier this year, Mrs Hatoyama also told a TV programme that she had met Tom Cruise in a previous life.
While she cautioned the interviewer not to take her too seriously, she said: "I know he was Japanese in a previous life.
"I was with him then. So he would recognise me when I see him and say 'long time, no see!'"
On the same talk show, she also described her unusual habit of "eating the sun".
Raising her arms into the air, she said: "I also eat the sun. Like this, hum, hum, hum. It gives me enormous energy. My husband has recently started doing that too."