The ghostwriter behind the man dubbed Japan's Beethoven has come forward a day after Mamoru Samuragochi admitted he did not create the famed musical works attributed to him, with the real composer even alleging that his better-known partner could be faking his deafness.

Takashi Niigaki spoke at a packed media conference in Tokyo Thursday, confirming that he has written music for Samuragochi for 18 years and noting that he ended their longtime "collaboration" last year after becoming fed up.

He explained that he would compose pieces and play them for Samuragochi, who would choose what he liked.

"The music was born of my collaboration with him," he said, adding he was paid about 7 million yen (about $76,000 Cdn) for composing more than 20 pieces for Samuragochi since 1996.

Niigaki, a 43-year-old part time music lecturer and teacher, became flustered when trying to answer the barrage of questions from reporters, including how he and Samuragochi managed to keep their deception going for so many years. He admitted that he questions whether Samuragochi is indeed deaf.

Mamoru Samuragochi

Mamoru Samuragochi, seen in December, has not commented on Niigaki's allegations. (Jiji Press/AFP/Getty Images)

"I saw no signs that he could not hear," Niigaki said. "We carry on normal conversations."

He added that Samuragochi vowed to commit suicide if Niigaki ended their arrangement, but that he felt compelled to come forward after learning that one of Japan's Olympians — figure skater Daisuke Takahashi — had decided to skate to Sonatina for Violin, one of the pieces attributed to Samuragochi.

"I was afraid that even Takahashi, who will perform in the Olympics for Japan, would be used to enforce the lies made by Samuragochi and me," he said.

Shock across Japan

Samuragochi's lawyer said Thursday he does believe his client has impaired hearing since he has a certificate that classifies him as having severe hearing loss. Samuragochi himself has claimed in past interviews that his hearing loss took place gradually in his 30s due to a degenerative condition.

The attorney made the revelations Wednesday on behalf of Samuragochi, who was in "too unstable an emotional state" to appear in public, but gave no reason why the musician was coming forward now.

On Thursday, a local media outlet published a tell-all interview with Niigaki.

The news has sent shockwaves across Japan, where Samuragochi's music is popular and widely featured. Along with his own concert tours, the compositions attributed to him are played during television broadcasts and have been used  as musical scores for top video game franchises such as Resident Evil and Onimusha.

His powerful Hiroshima Symphony (Symphony No. 1) — released in 2003 as a tribute to those lives lost in the 1945 atomic bomb attack on Samuragochi's hometown — was revived in recent years as a piece honouring Japan's tsunami survivors and became a classical bestseller.

With files from Agence France-Press and The Associated Press