They are animator
On Japanese animation process, the jobs between 動画マン and 原画マン are completely separated. Why I recommended you to know 動画マン's jobs and get experience as 動画マン first is because to prevent mistakes on your work in the future. This is the one of the reason. Actually there are many young animator who don't know accurate knowledges have worked on animation industry. How to write time-sheets, where is the best key positions (more and more a good animator, they don't use much pictures and times, I think), and they draw the terrible key frames which can't do in-between. So animator beginners have to build up basic skills during 動画マン. It is like 修行/Training
And we have a different problem in there
If we don't teach this to young people and to maintain the basic techniques, or else Japanese animation industry will be collapse definitely! I suppose that Japanese can't make a such amazing works AKIRA, JIN-ROH any more
How did they make it? I always think about this and study more