I actually like some of the 'original' manga - like Yoshitoshi's "One Hundred Views of the Moon" The original paintings are destroyed in the process of creating the blocks (sometimes there are over 100 blocks to print to make one complete print). His drawings and sketches for each painting/print (and others of course) are what eventually evolved into Mangas.
Okay, I take liberties with the history; Yoshitoshi was actually one of the last of the Ukiyo-e artists but I so love his work. There was a local art gallery that had collected samples of all 100 woodcuts - it was an amazing collections that showed what happens over time to such a complicated process. Original prints were stunning, but over time you can see that the blocks became worn from use and some of the blocks were missing (after 200 years, losing one or more of the 100-200 printing blocks is entrop at work).