This hairstyle is called Dai Yue. Originally, the Japanese studied China's costume and combed the bun on the top of their heads. However, in Muromachi era, samurai wore heavy helmets for a long time, and the shape of the bun was often messed up, which oppressed the top of their heads and brought pain. In order to relieve the pain on the top of the head, the samurai invented a hairstyle to remove or even unplug the hair on the top of the head, which was called "Dai Yue". Because removing the remaining hair on the top of the head is like a crescent moon.

Later, ordinary people also learned the form of samurai bun, which eventually became a social custom.

Fear of lice bites, for hygiene;