Why do anime have manga adaptations? Why don't authors just focus on one medium at a time?


Instead of having to work on both the anime and the manga at the same time,
why don't the authors just focus on one?




For this answer I am going to assume only works which began as an anime and
were later adapted into manga are under consideration. This is hard to study
nowadays because there are so few anime-original works, but in most of the
cases I know of, the manga is just tie-in merchandise for the anime, the same
way anime adaptations of manga are tie-in merchandise for the manga, or anime
and manga adaptations of light novels and visual novels are tie-in merchandise
for the light/visual novel.

Usually, the author of the manga is a contract worker of some sort: the studio
hires them to write and draw a manga version of the anime, sometimes while the
production of the anime is underway, and sometimes after it's finished. The
original team behind the anime doesn't usually work on the manga; their names
might be on the cover as a "Story" credit, meaning they're just being
acknowledged as the creator of the story. It's the reverse version of seeing
"Based on the manga by XX" in the opening credits of an anime. So having a
manga adaptation doesn't actually take any effort away from the anime; the two
productions go ahead independently, sometimes extremely so. For example, the
first manga adaptation of [The Vision of
Escaflowne](https://en.wikipedia.org/wiki/The_Vision_of_Escaflowne#Manga) was
based on an early version of the story from when Yasuhiro Imagawa was attached
as director. Imagawa left to direct G Gundam and the production was put on
hold, but the manga went ahead with his shounen version of the story, only to
become inaccurate later when Kazuki Akane came in and reworked the show as a
shoujo series.

Some anime also have spinoff manga, which aren't directly based on the
original anime. Evangelion, for example, has [Angelic
Days](https://en.wikipedia.org/wiki/Neon_Genesis_Evangelion:_Angelic_Days),
[Shinji Ikari Raising
Project](https://en.wikipedia.org/wiki/Neon_Genesis_Evangelion:_Shinji_Ikari_Raising_Project#Manga),
and [Campus
Apocalypse](https://en.wikipedia.org/wiki/Neon_Genesis_Evangelion:_Campus_Apocalypse).
Madoka has Kazumi Magica, Oriko Magica, Wraith Arc, The Different Story,
Homura Tamura, Homura's Revenge, Tart Magica, Suzune Magica, and probably soon
the epic crossover Puella Magi Mahoro Magica: The Resurrection. Like the
direct adaptation manga, these are passed off to hired help, but they often
have valid creative reasons for existing. Angelic Days and Shinji Ikari
Raising Project explored the banal world that Shinji creates in his mind in
Episode 26 of the anime. Wraith Arc and The Different Story fill in parts of
the anime storyline that weren't shown onscreen; Suzune Magica and Tart Magica
focus on different characters in the same world; Homura Tamura is a parody.
Since manga are cheaper to produce than anime, the spinoff manga are a low-
cost way to explore the world of an anime, or create alternative scenarios, or
to give hardcore fans something they want that doesn't have wide enough appeal
to fund another anime. Some of these spinoff manga, I don't care about, but
reading The Different Story totally changed my view of certain characters and
events in the anime series, so I'm glad that the anime staff didn't decide to
"just focus on one" and allowed the spinoff manga to be made.

