Steampunk Scholar discusses the elements of Steampunk in Hayao Miyazaki's 2004 feature film, Howl's Moving Castle:
To return to Howl, the retrofuturist elements are evidenced most clearly in the battle scenes: the technology of Ingary is anachronistic for the nineteenth century look and feel of the film. The film's war sequences are hybrids of both World Wars, with massive airships and dreadnought-style battleships that never existed, but evoke a sense of the past. This type of technology has been present in steampunk precedents and steampunk itself since its inception: consider the battle from Moorcock's Warlord of the Air, anthologized by the Vandermeers in their first Steampunk anthology, or the cover of Fitzpatrick's War with its endless rain of war machines in the background. If we were to say that steampunk is a genre concerned with war, we'd only be representing some steampunk texts, but not all: there are no epic sky battles in Morlock Night, or Rucker's The Hollow Earth. Instead, what appears in all of these is some retrofuturist concept - an idea of how the past viewed the future - in the case of steampunk, specifically how the past of the nineteenth and early twentieth century viewed the future. Miyazaki's designs for the war machines of Howl fall squarely within this aesthetic delineation.
So is it the application of the steampunk aesthetic that changes the themes of Howl from book to film? Kimmich argues the abandonment of the crosshatch element from the novel and the inclusion of the war Ingary is waging as responsible for the major divergence. As already noted, the steampunk aesthetic is utilized immediately, and Kimmich finds the first 30 minutes of the film faithful to the book: steampunk is not an impediment to crosshatch narratives, since Philip Pullman's His Dark Materials employs a steampunk aesthetic in Lyra's world, to good effect. Kimmich concedes the reasons for Miyazaki's rejection of the crosshatch elements as being necessary in adapting the novel to film, since the film could not create the same sense of unfamiliarity about our own world the novel achieves.