The show alternates between traditional animation and cel-shading a lot.
There are also animated series produced exclusively via cel shading, usually for similar reasons.
In other media, Cel Shading can be useful to render specific items in a hand-drawn production, if a given scene would be too difficult to animate by hand, such as a rotating object or an Epic Tracking Shot traveling down the length of a massive vehicle. While the style is not exclusive to Video Games, it is often used there since this is the only way to produce a hand-drawn look via computer polygons. The style was codified with the Sega Dreamcast game Jet Set Radio. In layman's terms, it imitates the look of hand-drawn artwork and animation. Cel Shading is a style of computer rendering that replaces the shading gradient of conventional rendering with flat colors and shadows (as seen at right).