Classical music composer and pianist Mamoru Samuragochi — a popular, deaf artist hailed as Japan's Beethoven — has sent shockwaves through the country with his admission that someone else has actually been behind his compositions for nearly two decades.

"Samuragochi is deeply sorry as he has betrayed fans and disappointed others. He knows he could not possibly make any excuse for what he has done," read a statement from the musician.

A lawyer representing Samuragochi shared the revelation with media, noting that the composer's music, including his best-known work Hiroshima Symphony (Symphony No. 1), has been written by another person since 1996.

The 50-year-old Samuragochi "deeply regrets" the situation and "is mentally distressed and not in a condition to properly express his own thoughts," said the lawyer, who requested anonymity.

"I've been told that there are certain circumstances that make it hard for the person [who composed the works] to come out in public, and Samuragochi has come to describe himself as the sole composer," the lawyer added.

He explained that, under an agreement between the two, Samuragochi shared ideas and concepts for new compositions with the unknown individual, who then proceeded to write the actual pieces.

The real composer behind his music has not responded to media appeals for comment.

Ripples throughout Japan

Born in Hiroshima to the survivors of the atomic bomb, Samuragochi learned to play the piano from his mother as a toddler. Described as a self-taught composer, he gained fame for well-received classical compositions created for films and video games franchises such as Onimusha and Resident Evil.

Around the age of 35, after years of suffering migraines and a degenerative condition that affected his hearing, he became completely deaf. However, he claimed he was able to continue working by relying on his "inner sense of sound."

Samuragochi's Hiroshima Symphony was released in 2003 as a tribute to those killed in the bombing of his hometown in 1945.

The work became popular again last year after public broadcaster NHK aired a documentary showing the pianist touring tsunami-battered regions to meet survivors.

The revelation has prompted reactions throughout Japan, where Samuragochi's music is featured widely.

Organizers for his ongoing concert tour are evaluating whether to continue while a music publisher has cancelled an upcoming release of a new Samuragochi musical score. His record label, Nippon Columbia Co., said it would stop sales and shipments of his albums.

Various television stations — from NHK to Tokyo Broadcasting System — apologized to viewers for having featured music he was believed to have composed.

Even one of Japan's Olympians, figure skater Daisuke Takahashi, has been caught up in the situation: Takahashi's program for the 2014 Olympic Winter Games in Sochi reportedly includes a piece of music that was allegedly composed by Samuragochi several years ago.