World-renowned Japanese musician and composer Ryuichi Sakamoto, also the keyboardist of the legendary electronic music band Yellow Magic Orchestra, known as YMO, has died, his office said Sunday. He was 71.

Sakamoto revealed in June 2022 that he had been battling stage IV cancer. The Tokyo native also starred in the 1983 war film "Merry Christmas, Mr. Lawrence," and won an Oscar and Grammy for scoring the 1987 movie "The Last Emperor."

Ryuichi Sakamoto speaks in an interview on March 25, 2017 in Tokyo. (Kyodo)

A funeral for Sakamoto, who died last Tuesday, was already held with only close relatives in attendance, the office said. The exact cause of death was not immediately known.

With his interest in environmental and peace issues, Sakamoto had been actively involved in the anti-nuclear power movement in recent years in the wake of the 2011 Fukushima nuclear disaster triggered by a killer earthquake and tsunami.

The son of Kazuki Sakamoto, a renowned editor at the publishing house Kawade Shobo Shinsha, Sakamoto began studying music writing at the age of 10 and was fascinated by the Beatles and Debussy.

As a high school student in the late 1960s, he participated in student demonstrations. Later, in an interview, he revealed that this experience "was at the core of who I am."

In 1978, Sakamoto formed YMO with Haruomi Hosono and Yukihiro Takahashi. Their futuristic techno-pop music, making full use of synthesizers, was in sync with the times in the late 1970s, when the movie "Close Encounters of the Third Kind" and the arcade game "Space Invaders" became hits.

In January, Takahashi, the drummer of YMO, died of aspiration pneumonia.

File photo taken in July 2010 in Yokohama shows Ryuichi Sakamoto (C) with Yellow Magic Orchestra bandmates Yukihiro Takahashi (L) and Haruomi Hosono. (Kyodo)

Dressed in clothing resembling Mao suits, the trio's performances were well received in the United States and Europe, and their music, such as "Technopolis" and "Rydeen," from an album released in 1979, became popular in Japan following their success overseas. YMO's hit tunes also include "Kimi ni Mune Kyun" (my heart beats for you), a single released in 1983.

Having obtained a master's degree from the Graduate School of the Tokyo University of the Arts, Sakamoto was known for his theoretical views and vast knowledge of classical and folk music, earning him the nickname "Professor."

He scored more than 30 films, including Nagisa Oshima's "Merry Christmas, Mr. Lawrence," in which he also played the role of a Japanese commander of a prison camp, "The Last Emperor" and "The Sheltering Sky," both directed by Bernardo Bertolucci in 1987 and 1990, respectively.

File photo shows the team that created the film "Merry Christmas, Mr. Lawrence" in Paris on May 11, 1983: (from L) producer Jack Thomas, musical composer Ryuichi Sakamoto, star David Bowie and director Nagisa Oshima. (AP/Kyodo)

File photo shows Ryuichi Sakamoto playing the keyboard during Yellow Magic Orchestra's reunion concert at Tokyo Dome in June 1993. (Kyodo)

The musician also led More Trees, a Tokyo-based forest conservation group established in 2007.

Sakamoto, who began spending most of his time in New York in the early 1990s, went public with his throat cancer diagnosis in 2014 and his rectal cancer diagnosis in 2021. Cancer later spread to his lungs, requiring him to undergo surgeries in October and December 2021.

Sakamoto discussed in detail his cancer diagnosis and how he had been coping with it in an article titled "Living with Cancer," published by the literary magazine "Shincho" in June 2022.

The article was the first installment in a series of articles titled "How Many More Times Will I See the Full Moon?" that the musician authored in the monthly magazine, dealing mainly with his musical activities and his views on life and death.

In a statement he released on the launch of the series, he said, "Since I have made it this far in life, I hope to be able to make music until my last moment, like Bach and Debussy, who I adore."

Sakamoto was one of the few Japanese celebrities in the entertainment industry willing to make political statements, including saying following the 9/11 terror attacks in 2001 that the situation surrounding the attacks was "created by the hegemonic nation of the United States."

After the magnitude-9.0 quake and ensuing tsunami devastated northeastern Japan in 2011, he became music director of the Tohoku Youth Orchestra, formed by children affected by the disasters.

File photo shows Ryuichi Sakamoto (4th from L) posing with members of the Tohoku Youth Orchestra as its music director on March 31, 2019 in Tokyo. (Kyodo)

In March 2022, while battling stage IV cancer, Sakamoto took part in the orchestra's concert in Tokyo, in which a new symphony he composed, titled "Ima Jikan ga Katamui te" (now the time is tilting), was performed.

The symphony ends with the sound of bells, and he explained to the audience from the stage that earthquakes and wars share the same prayer for the repose of souls who were killed.

The concert was held amid Russia's invasion of Ukraine, and he noted that the symphony has some similarities to Ukraine's national anthem, adding, "It is up to each one of you to decide whether the sound of the bells (at the end of the symphony) sounds like a requiem or hope."

Singer-songwriter Akiko Yano is his former wife, and musician Miu Sakamoto is his daughter.

Related coverage:

Composer Ryuichi Sakamoto calls for stop to Jingu redevelopment plan

Yukihiro Takahashi, drummer of legendary Japan band YMO, dies at 70