A Japanese man named Ryuho Okawa claims he spoke to Princess Diana's "lonely" spirit, The Mirror reported.

In his country, Ryuho Okawa is known as "renowned spiritual leader", the report revealed. Okawa released a book on their conversation entitled Spiritual Interview, just prior to her 20th death anniversary. It is currently sold on Amazon

While there are many tributes to Diana on her death anniversary, this is for sure the strangest. Okawa claims he summoned the princess earlier in August at a lecture hall in Japan. According to him, Diana was "invited by the International Division of Happy Science to speak to Okawa and his fellow psychics," The Mirror reported.

He claims they talked about Queen Elizabeth, Prince Charles and the night she died where she was killed in a car accident in Paris.

Okawa also claims Diana's "spirit" believes the British Royal family could soon come to an end and face a revolution. Speaking about Kate Middleton, her son William's wife, Diana "said" she is kind to her.

However, the biggest claim was about Prince Charles. When Okawa asked if she could forgive him, the spirit reportedly said: "No, definitely no. No, no, no. I don't hate him, but I believe that he's a devil."

The interview takes an even more dark twist when he asked her if someone killed her. According to the report, in the book the spirit is quoted as saying: "I'm not sure, but I felt some kind of evil intention."

"Maybe secret service or... Someone was aiming to deprive me of my life after I got a divorce. It's from Charles or..."

"He can send some messenger of death."

Okawa founded Happy Science in 1989, a movement dedicated to bringing "happiness to humankind". He has also reportedly sold more than 100 million books on a range of topics.