noun
key animator; lead animator
In animation production, the person who draws the main keyframes that define the motion; often contrasted with 動画マン (in-between animator).
彼はアニメスタジオで原画マンとして働いている。
He works as a key animator at an anime studio.
原画マンが描いた絵をもとに、動画マンが中割りをする。
Based on the drawings by the key animator, the in-between animator does the in-betweening.