Kazuki Takahashi, the author of the popular "Yu-Gi-Oh!" manga series, has been found dead after an apparent snorkelling trip in Japan, a coast guard official said Thursday.

The 60-year-old was found off the coast of Okinawa in the country's south on Wednesday.

He was wearing a T-shirt and an underwater mask, snorkel, and fins, the official in the city of Nago, who declined to be named, told AFP.

"We are investigating the case as both a possible accident or crime," he said.

Japanese media including public broadcaster NHK said Takahashi was found around 300 meters offshore and pulled from the water.

"Yu-Gi-Oh!" ran in the Japanese weekly comic magazine Shonen Jump between 1996 and 2004.

It told the story of Yugi, a teenager who receives an ancient puzzle that awakens in him the alter ego of an Egyptian pharaoh.

The manga gave rise to a media franchise including a trading card game as well as anime series and films.

It was later published as a series of 38 books by Japanese publishing powerhouse Shueisha, which did not issue an immediate statement on Takahashi's death.

Takahashi wrote under a pen name and his real first name was Kazuo.