Okami's signature mechanic, the Celestial Brush, asks the player to stop moving the controller like a joystick and instead draw. At almost any point in the game the world can be paused mid frame and painted over: a stroke through a dead tree brings it into bloom, a circle drawn in the sky becomes the sun or the moon, a straight line slashed through an enemy becomes a sword cut. The tool is explicitly one of the thirteen legendary brush techniques the game attributes to Amaterasu herself, restoring a corrupted world by the same divine hand that, in the myth the game draws its premise from, is said to have shaped it originally.
The visual language built around that mechanic borrows directly from sumi-e, the East Asian ink wash painting tradition, rendered throughout in muted washes, visible brush texture and deliberately incomplete linework rather than the fully rendered three dimensional environments typical of games released around it in 2006. Clover Studio's director, Hideki Kamiya, and art director, Kenichiro Yoshimura, have both discussed the choice as inseparable from the subject matter: a game about a Shinto sun goddess restoring a poisoned land needed, in their account, to look like the tradition of painting Shinto and Buddhist religious subjects had actually looked, not like a generic fantasy adventure that happened to be set in Japan. The result was singled out by reviewers on release as one of the most distinctive art styles in the medium, and remains the game's most frequently cited achievement across every platform it has since been ported to.