With a title that somehow suggests porn or horror, this gentle, wistful anime triptych by Makoto Shinkai (The Place Promised in Our Early Days) is actually about the passage of love and time, measured by the changing seasons. Five centimeters per second is the velocity of falling cherry blossoms, according to preteen puppy lover Akari, who's separated from her bookish b.f. Takaki when his family moves away. The three gorgeously rendered movements cover their middle-school crush, his lonely time away during high school, and their fleeting adult connection back in Tokyo. The third and shortest section is essentially a music vid for an awful J-pop power ballad ("I pray!—for the seasons to stand sti-iiiiill!"), but the prior installments are often breathtakingly beautiful. Shinkai and his animators convey all the longing, uncertainty, and regret with delicate tableaus—pastel skies looming over the wandering schoolkids; a train stopped between stations in the feathery snow; the stars pressing down with near-burdensome weight as Takaki's face is bathed in the cell phone glow of text messages he composes to Akari but never sends. Each chapter is animated with subtly different visual cues as Takaki ages from gauzy innocence to aching adolescence to a somewhat bitter young adulthood of crumpled beer cans and cigarette stubs. We never had it so good as when we were young, the film suggests, and we never stop obsessing over it later.