Seriously, I can think of at least some 4 levels at which this movie operates...

...and it's just goddamn brilliant in every single one of them.

A gleefully tongue-in-cheek satire of your run-of-the-mill jidaigeki? Check.

A touching, heartfelt fairytale? Check.

A riveting, check-your-brain-at-the-entrance adventure flick? Check.

A reverential love letter to, as well as an unapologetically caricatural parody of, Japanese history? Check.

Seriously, I've just watched it, and I'm in absolute awe; I can't imagine a single good reason for my never having heard of it before. This is, by any metric I can conceive of, an absolute cinematic masterpiece.