People who are employed during election campaigns to rally support for candidates from campaign trucks equipped with loudspeakers have been known as uguisu-jō — meaning “bush warbler ladies” — because the task has typically been assigned to women with melodious voices.

In recent years, however, they have been increasingly referred to as shajō-undōin (campaign staff on vehicles) due to gender considerations.

Some of the women engaged for the role say they had faced discrimination and harassment in the past — it's hard to see from the outside the conditions in which campaign teams operate — but they add that this is gradually changing.