Isao Tomita, the synthesizer pioneer who composed the score for Tezuka Osamu’s anime “Kimba the White Lion” and NHK drama “Hana no Shogai,” died of heart failure Thursday at Tokyo Metropolitan Hiroo Hospital. He was 84.

On Sunday, a message on Tomita’s official Facebook page said he was working on a new musical titled “Dr. Coppelius” and that he knew he might not see it finished.

“My priority right now is staying healthy, but I’d like to finish ‘Dr. Coppelius’ as much as possible so that, even if something happens to me, others could finish it,” Tomita told The Japan Times last December.

A private funeral on Saturday and Sunday was attended by close family members only.

Tomita helped spread electronic music in Japan after importing a Moog III synthesizer in 1971, when the instruments were expensive and rarely used.

He was a noted influence on the nation’s other noted electronic music pioneers, including Ryuichi Sakamoto of the techno-pop group Yellow Magic Orchestra.

The album “Snowflakes are Dancing,” which covers the music of French composer Claude Debussy, topped Billboard’s classical music chart in 1974 and was nominated for four Grammy Awards, making him the first Japanese to be nominated.

In 2014, four of its tracks, “Clair de Lune,” “Gardens in the Rain,” “The Engulfed Cathedral” and “Snowflakes are Dancing,” were used in the American film “Heaven Knows What.”

Tomita had recently been working on projects that experimented with virtual diva Hatsune Miku, a singing computer program produced by Crypton Future Media.

The first such project, “Symphony Ihatov,” premiered in 2012 after being inspired by writer Kenji Miyazawa’s novels. It featured Miku singing along with the Japan Philharmonic Orchestra.

Last year Tomita won the Japan Foundation Award and spoke about “Dr. Coppelius” during a related event. The project was dedicated to Tomita’s longtime friend, Hideo Itokawa, the father of Japanese rocketry, who dreamed of creating a hologram in the form of a ballet dancer.

With backup by Crypton Future Media, “Dr. Coppelius” was scheduled to be performed in Shibuya’s Bunkamura on Nov. 11 and 12 featuring a 3-D hologram of Hatsune Miku.