Four stars. Rated PG. 101 minutes. “If you must blink, do it now,” begins the voice-over narration of the animated adventure “Kubo and the Two Strings.” “Pay careful attention to everything you see, no matter how unusual it may seem.” A viewer would do well to heed that advice, not only because this breathtakingly beautiful film comes courtesy of Laika, the stop-motion animation studio behind the Academy Award-nominated eye-poppers “Coraline,” “ParaNorman” and “The Boxtrolls.” As hinted at in the second part of that warning, “Kubo” is both extraordinarily original and extraordinarily complex, even for a grown-up movie masquerading as a kiddie cartoon (which it kind of is). While the movie will certainly appeal to many children – with its juvenile protagonist (voice of Art Parkinson), talking monkey sidekick (Charlize Theron) and occasional comedy, mostly provided by Matthew McConaughey as a samurai warrior who has been turned into a giant, joke-cracking beetle — it is also richly allusive and metaphorical in ways that take some maturity to suss out. It’s also, especially for younger viewers, pretty darn scary. The action begins when a young Japanese boy named Kubo accidentally raises the malevolent, ghostlike spirits of his two maternal aunts (both voiced by Rooney Mara).