It is generally a waist-length or knee-length haori, without a folded collar or chest strap, and is characterized by its simple shape with tubular or wide sleeves.
Originally, samurai warriors wore happi coats with their family crests dyed in large letters, and then craftsmen and firefighters began to wear them. The original happi was a single-layered kimono with a chest strap, while the hanten was a lined kimono, but the distinction was lost in the late Edo period. By inserting letters (collar letters) vertically from the collar to the chest, the wearer's affiliation, name, or intention can be expressed. For example, "Carpenter Tomekichi," "Megumi Koto," and "Irasshaimase. For happi coats used in festivals, collar letters such as "Gosaire," "Wakamutsumi," "Nakawaka," and "Kowaka" are added to indicate affiliation and age.
In the fire department, it is still the uniform of the firemen, and can be seen at the ladder rides at the first ceremonies (the Fire and Disaster Management Agency's "Firemen's Uniform Standards" calls it the "B-class robe. (According to the Fire and Disaster Management Agency's "Firemen's Uniform Standards," it is called the "Class B robe," but not all firemen are loaned this robe. This is the origin of firefighting. This is a tradition that dates back to the early days of firefighting. In recent years, it has been used not only for fire-fighting teams and festivals, but also for cheering for professional baseball and other sports, and for costumes worn by shopkeepers during sales at department stores. In addition, Japan Airlines used happi coats for many years as in-flight wear for its first class passengers.