A happi (法被/半被) is a traditional tube-sleeved Japanese coat, usually worn only during festivals.
Happi typically feature symbols and/or text on the lapels, with a larger design on the back of the coat, typically the name or the festival or the participating association; the kanji for ('festival' (祭り, matsuri)) may also be present.
'embroidered fireman's jacket') also worn by firefighters, constructed from heavily-quilted cotton layers designed to hold a large quantity of water and thus protect the wearer.
Thus, wearing conspicuous happi and dancing on intact roofs near fires with matoi was essential for them.
Happi are typically blue, with designs in red, black, and white, though variations with a number of different colours are also seen in modern day Japan.