Young Anna is sent to live with relatives in the country for a summer (as are the protagonists of all Japanese movies), where she solves family mysteries by befriending the ghost of her grandmother.
Sometimes the mystery aspects seem slow-moving since Anna is oblivious to details we pick up right away, but the movie is pure pleasure, beautifully animated, with lovely details. Her dreams and fantasies mix with reality, she forgets things within and without them, seems to sleepwalk and lose track of time, and it all makes for a more emotionally complex experience than a plot summary would imply.
T. Robinson for The Dissolve last year:
It’s still possible there will eventually be more Ghibli features. It’s just hard to imagine that a reduced studio staff could keep up the lavish, loving quality of When Marnie Was There, the last movie on Ghibli’s animation docket. Like so many Ghibli features, Marnie is an accomplished animated showcase. But this time, the images seem particularly lustrous, the colors especially rich. If the studio has to cut back from here, at least it’s set yet another high-water mark before the tides recede.
…
in spite of the third-act reveal, Marnie isn’t really a movie about surprises. Like so many Ghibli films, it’s about the power of emotion. Anna’s transformation from faint-hearted and miserable to enthusiastic and engaged with the world closely mirrors the transformations other Ghibli heroines have gone through, from Chihiro in Spirited Away to Kiki in Kiki’s Delivery Service to SofĂ® in Howl’s Moving Castle. Her change in attitude changes her ability to perceive truths about the world she’s been unable to accept.