Happi are the team uniforms of Japanese festivals. They are a simple cotton vest adorned with the emblem of a shine, temple, team, company, school or shop.
Happi date back to the 19th century. They were once used as uniforms by firefighters and shop staff all over the country. Some shop staff still wear happi today.
Matsuri happi are a simple and economical uniform for festival activities. They are often used to identify a mikoshi team or official members of a shrine. Anyone wearing a happi has some official relationship to the festival. In most cases, they are reused year after year.
They are typically worn with an undershirt and short shorts or regular pants. In some cases, men wear fundoshi. Happi often come with matching headbands.