Abstract This article begins to develop an understanding of surgical mask-wearing in Japan, now a routine practice against a range of health threats. Their usage and associated meanings are explored through surveys conducted in Tokyo with both mask wearers and non-mask wearers. It contests commonly held cultural views of the practice as a fixed and distinctively Japanese collective courtesy to others. A historical analysis suggests that an originally collective, targeted and science-based response to public health threats has dispersed into a generalised practice lacking a clear end or purpose. Developed as part of the biomedical response to the Spanish flu of 1919, the practice resonated with folk assumptions as making a barrier between purity and pollution. But mask-wearing became socially embedded as a general protective practice only from the 1990s through a combination of commercial, corporate and political pressures that responsibilised individual health protection. These developments are usefully understood amidst the uncertainty created by Japan�s �second modernity� and the fracturing of her post-war order. Mask-wearing is only one form of a wider culture of risk; a self-protective risk ritual rather than a selfless collective practice.