"Ee ja nai ka was a complex of carnivalesque religious celebrations and communal activities, often understood as social/political protests, which occurred in many parts of Japan from June 1867 to May 1868, at the end of the Edo period and the start of the Meiji restoration. The movement originated in the Kansai region, near Kyoto.
In West Japan, eejanaika appeared at first in the form of dancing festivals, often related to public works, rain magic, or dances for the dead. When sacred amulets were said to have fallen from heaven, thanksgiving celebrations for these amulets were added that could last for several days and effectively took whole rural and urban communities away from everyday life. Gifts were exchanged, youth groups organized mass dancing including cross-dressing, wearing costumes, or not wearing clothes at all. To express their gratitude towards the gods or buddhas who had given them the amulets, many people went on pilgrimages to local or regional sanctuaries. The term ee ja nai ka was a refrain in popular songs performed during these activities and was therefore later chosen as their title. The phrase's meaning is both defiant and fatalistic, and it translates as "Who cares?", "Why not?", or "What the hell?", along the lines of "'Who cares if we take our clothes off," "Who cares if we have sex.'"