noun
amanuensis; ghostwriter; scribe
Refers to a person who writes something for someone else, such as a letter, document, or literary work. Can range from a formal secretary to a ghostwriter.
彼は有名作家の代筆者として長年働いた。
He worked for many years as a ghostwriter for a famous author.
目の不自由な方のために、代筆者が手紙を書いた。
An amanuensis wrote a letter for the visually impaired person.