“… as can be seen from portraits of activists at the time of the Restoration, or illustrated accounts of the exploits of the Shogitai, men began to let their forelocks grow out and to tie their hair back in a simple ponytail bound with a thick purple cord. The popularity of this fashion reflected the demand for a style suited to an active life. In Mito, though, older people condemned it as frivolous and vain.”
Yamakawa Kikue, Women of Mito Domain p. 55, translated Kate Wildman Nakai
Some context for Hijikata’s hairstyle in Hakuouki!