The 2003 Fullmetal Alchemist anime, as we all know, departed significantly plot-wise from the manga. The mangaka for FMA is Hiromu Arakawa. Did she have any input on the plot or production of the 2003 anime, or was it written by other people just based on the manga?
It was directed by Seiji Mizushima, written by Shō Aikawa and co-produced by Bones, Mainichi Broadcasting System and Aniplex. Character designs by Yoshiyuki Itō. During the making of the anime, Arakawa was present in meetings to advise the staff about the world of Fullmetal Alchemist, though she did not write for the television series.