A genjutsu-created alternate world where key character histories played out differently from the main continuity.
Doesn't advance the main plot — optional viewing for fans wanting a distinct "what if" experience with familiar characters.
No — it's a non-canon, standalone alternate-universe film, generally considered optional viewing rather than essential to the main storyline.
Its alternate-universe premise lets it explore character dynamics and relationships that don't exist in the main continuity, offering a distinct "what if" take on familiar characters.