Hikōtei Jidai
Hikōtei Jidai (飛行艇時代, lit. The Age of the Flying Boat) is a fifteen-page, all-watercolor manga, on which the animated film "Porco Rosso" is based. It was published in Model Graphix in three parts, a monthly magazine about scale models, as a part of Hayao Miyazaki's "Zassou Note" series. Like other manga in this series, "Hikōtei Jidai" is a manifestation of his love for old planes. It is filled with aircraft from the 1920s (heavily modified by Miyazaki) and their technical details, as well as with the men (good-hearted and silly) who love them.
Hikōtei Jidai was published in 1992 by Dainippon Kaiga (ISBN 4-499-20595-6)
It is a book of about 60 pages, includes the 'Porco Rosso' manga (15 pages total), several airplane vignettes, resin-kit models of aircraft, photos of some real counterparts of the floatplanes which appeared in the film, and some interviews with Miyazaki regarding airplane model kits.
Differences from Porco Rosso
Compared to the anime version, the manga is much more light-hearted. Other than being a "retired Italian Air Force pilot", Porco's past is not discussed, although the rise of fascism and the sentiment against it are mentioned. Gina doesn't appear at all, and Porco is much more lighthearted. Still, the basic story line and its charm are carried over into the anime.