Originally released in 1988, it actually took 10 years for Miyazaki to fully develop the story, while still making changes halfway through production. The idea for the film came during a time when Miyazaki was most unhappy about his career. He had just been offered to do a children's show on a Japanese television network, but he knew if he accepted, he would be giving up his own artistry and point of view. So, instead, he began writing what he thought would be a children's book, which ended up being a life-changing story.
*The original article can be seen here.*