Twenty lucky Harry Potter fans in Japan have won the privilege of looking inside a rare handmade book by author J.K. Rowling, an offshoot of the bestselling series.

Online bookseller Amazon unveiled the silver-studded, leather-bound book of five tales of wizardry at a news conference in Tokyo on Friday.A Sotheby's staff member displays the manuscript The Tales of Beedle the Bard by J.K. Rowling, sold to Amazon for $4 million US.A Sotheby's staff member displays the manuscript The Tales of Beedle the Bard by J.K. Rowling, sold to Amazon for $4 million US. Sang Tan/Associated Press)

There are only seven copies of The Tales of Beedle the Bard, which Rowling wrote and illustrated by hand — in essence, the first book she's written since the Potter series.

The 42-year-old writer said she would only ever sell one copy with the others given to people closely connected to the Harry Potter novels, which have sold 400 million copies worldwide.

Amazon bought that one copy for $4 million US at an auction in December, with all of the proceeds channelled to one of Rowling's favourite charities, The Children's Voice, which helps children in care in Eastern Europe.

For Potter fans in the know, The Tales of Beedle the Bard was left to Hermione Granger by Hogwarts head teacher Albus Dumbledore. It contains clues to help Harry and his friends defeat his nemesis Lord Voldemort.

The stunt in Tokyo was part of Amazon's promotion of the release of the Japanese version of Harry Potter and the Deathly Hallows, the final instalment of the series.

The book goes on sale in Japan at the end of July.