Hitchhikers are rare in Japan and even in the United States, where they once flourished. Having crisscrossed North America by thumb, sometimes for weeks and months on end, I can say that riding with random strangers is a learning experience. It is also dangerous.

Both elements are present in “Yoko,” a stark and powerful road movie by Kazuyoshi Kumakiri that won three prizes at this year’s Shanghai International Film Festival, including best film, best screenplay and best actress for a bravura performance by Rinko Kikuchi.

Kosuke Muroi and So Namiko’s script papers over its improbabilities, the primary one being the need for Kikuchi’s 42-year-old titular protagonist to hitchhike instead of heading for the nearest train station. I didn’t quite buy her reasons, beginning with her apparent lack of credit or debit cards and that necessity of modern life — a working smartphone.