Old Man Sakaki is a character in the On the Way to a Smile novella "Case of Barret". According to Barret Wallace, Sakaki designed several prosthetic arms for Barret after the destruction of Corel, including a hammer-arm, shovel-arm, and hook-arm, but these failed to satisfy him. Sakaki eventually gave Barret an adapter that could attach multiple prosthetics — or weapons — and told Barret that he was consumed with thoughts of revenge against Shinra, and so no attachment Sakaki could devise would please him.
Years later, Barret returned to Sakaki and requested a prosthetic hand so he could live a normal life. Sakaki tells Barret it will take a week, and has him work helping his nephew in the meantime. When Barret returns, Sakaki presents him with a wooden prosthetic, but Barret tells him he still has fighting to do. Sakaki then reveals a steel hand for Barret, which he designed for him years ago, which Barret takes.