Even after years of etiquette posters and tutting on social media, there’s still a significant chunk of the population in Japan who’d rather risk censure than give up their seat on a busy train. For high school dropout Karin (Karin Ono), the protagonist of Izuru Kumasaka’s “Pretenders,” this simple act of kindness proves dangerously inspirational.

“Maybe he was a metaphor for the world,” she gushes to her best friend, Fuko (Ai Mikami), after offering her seat to a needy passenger while heading to Tokyo’s Shibuya shopping district. And the world, as any headstrong 17-year-old knows, could always use a bit of improvement.

Drunk on altruism, the pair start creating opportunities for others to experience the joys of doing good. Calling themselves the Pretenders, they embark on a campaign of candid camera-style stunts for a noble cause. Karin poses as a blind woman and lets people help her cross the street; Fuko fakes a medical emergency, then waits for the good Samaritans to descend.