Flash mobs may not seem like events that need government oversight, but Japanese authorities see things differently. The mayor of Ebina — a city west of Tokyo — prohibited these gatherings in March, claiming that they violate local ordinances against public performance. Those charged with breaking the rule must pay five thousand yen — about fifty dollars.

The mayor’s decision came after Mothers’ Action for Peace and Democracy organized a flash mob in February. They were protesting the government’s controversial security legislation, which would give Japan permission to engage in foreign conflict and seems to be the first step toward revising the country’s pacifist constitution.

Dressed in black, denim, and sunglasses, members of Mannequin Flash Mob Kanagawa — a spinoff of Mothers’ Action — walked around Ebina Station’s raised walkways, carrying signs with messages critical of Prime Minister Shinzō Abe. At set intervals, one or two would stop on the busy platform and pose like a mannequin. The rest joined the stationary group one by one. They stayed motionless for short periods before moving on and repeating the performance in another part of the station.