It pains us to bring news of innocent mistakes that blow up huge, but this one is a real head-scratcher: It looks like copies of Okami for the Wii shipped with an IGN watermark on the cover art. See:
That means whoever designed the cover may have googled Okami and used the results instead of getting the art from Capcom.
FYI: Watermarks are those annoying digital marks websites use to proclaim that they have been sent a screenshot from a videogame maker. That way, other site owners might be less likely to pull it down and host it themselves.
By the way, G4's massive screenshot library is watermark free!
Kotaku: IGN Watermark in Okami Cover Art