The supervisor and overseer of the anime production is Kishimoto himself. He verifies the content the animators present him, and approve it as well.
In a way it is Canon, though not entirely.(Few fillers have way too much inconsistencies with the manga).
Take the Kakashi-Itachi ANBU Arc for example. It's safe to say this is Canon, and Kishimoto approved and supervised the story here. It would be Canon since it's filling in gaps in the manga storyline.
In a way it is Canon, though not entirely.(Few fillers have way too much inconsistencies with the manga).
Take the Kakashi-Itachi ANBU Arc for example. It's safe to say this is Canon, and Kishimoto approved and supervised the story here. It would be Canon since it's filling in gaps in the manga storyline.