The practice of wandering through a neighbourhood – in this case Tokyo’s Shimo Kitazawa en mass and picking up litter. Common enough in Japan, sometimes spotted as part of sponsor-a-highway campaigns in the US.

Of note in this context: it’s a Sunday and the neighbourhood is roughly equivalent to the Camden Town, Williamsburg or Prenzlaurberg – studenty-trendy give or take; the group are in their early 20’s – at an age when peer group affiliation and appearance is at the fore; they are wearing uniforms; the task they are engaged is non-glamorous and benefits the community. Welcome to the social.