Yu-Gi-Oh manga creator Kazuki Takahashi has been found dead, with his body discovered in the waters off Nago, Okinawa Prefecture on July 6. According to NHK via The Japan Times, Takahashi was “found floating while wearing snorkeling gear” and his body was recovered by the Japanese coast guard.

Takahashi’s manga career began in 1982 with series such as Fighting Hawk and Tennenshoku Danji Buray, but it was 1996’s Yu-Gi-Oh that saw him make his mark in the industry. The manga originally featured several stories about protagonist Yugi Mutou and his dark alter-ego who resolved conflicts by playing deadly games with his enemies, but it was the Duel Monsters card game featured in the series that saw its popularity massively increase over time.

Released in 1999, Takahashi used his experience in games design to create the general outline of the game, which took the world by storm. Sales of the manga multiplied after the card game was released, a new anime series was produced, and video game adaptations weren’t far behind.

Yu-Gi-Oh is still a best-seller in the card game industry and several of its spin-off anime series have run for multiple seasons. The latest video game adaptation, Master Duel, has proven to be so popular that publisher Konami was able to record its most profitable financial year ever.

Before his death, Takahashi was involved in the creative direction of the Yu-Gi-Oh franchise and had collaborated with Marvel on a Spider-Man and Iron Man graphic novel that was released last month.