rough draft of a book; draft manuscript; dummy comic book
Refers to a preliminary version of a book or a mock-up comic used for layout or planning. The 'dummy comic book' sense is common in manga production.
I submitted the draft manuscript to the editor.
The manga artist first makes a dummy comic book before starting on the final manuscript.
下書き is a rough draft or sketch, not necessarily in book form. 草稿本 implies a more complete draft in book format.
Compound of 草稿 (draft) and 本 (book). The term is straightforward and likely a modern coinage for publishing contexts.