"Music producer 'N.Y.' who's even recognized overseas has a number of ghost writers. He himself writes songs, but there's no way he can keep producing at that pace while maintaining such a high quality, and he has a team working for him. There's also 'T' who became popular after producing idols, 'G' who came from a visual band, and ikemen 40-y/o singer 'F.M.' who are all said to be using ghost writers within the industry. When it comes to writing the lyrics, songstress 'H.A.' and idol group producer 'A.Y.' also have their own ghost writers.". - (music insider)
These may be different from Samuragochi who has a hearing impairment, but the existence of ghost writers is reportedly rampant within the industry.
"Everyone gets into a slump, and even their speed in composing songs may take a dip, which is why there are a lot of ghost writers in order for the artists to maintain their sales. These are mostly done through agreements between the agency and the record label. It's also hard to imagine that the people around Samuragochi didn't know about his secrets, and probably just turned a blind eye in order to create a dramatic and touching story for the people." - (same source)
