IllustStudio is a drawing and painting application, created by CELSYS (who also created ComicStudio, known in the US as MangaStudio), specialized for creating full color illustrations. It provides a fully customizable user interface that can be configured to mimic a large number of popular competing software packages, such as Photoshop and PaintTool SAI. In addition to that, it also provides several functions useful to illustrators, including perspective rulers and layers containing 3d models with posable skeleton.