The rokurokubi (ろくろくび) curse only affects women. By day, rokurokubi appear to be ordinary women. By night, their bodies sleep while their necks stretch to incredible lengths and roam around freely. Sometimes their heads attack small animals; sometime they lick up lamp oil with their long tongues; and sometimes they just cause mischief by scaring nearby people.
Unlike most yōkai which are born as monsters, rokurokubi and their close relatives nukekubi are former humans—transformed by a curse resulting from some evil or misdeed. Perhaps they sinned against the gods or nature, or perhaps they were unfaithful to their husbands. In many cases, their husbands or fathers actually committed the sin and by some cruel twist of fate the men escape punishment and the women receive the curse instead.
An old tale from Tōtōmi Province (Shizuoka Prefecture) tells of a monk who eloped with a young lady named Oyotsu. While traveling, Oyotsu became sick. Treating her would have used up all of their travel money, so the monk murdered Oyotsu and stole the remaining money. On his travels, he stayed at an inn owned by a man with a beautiful daughter. The wicked monk shared a bed with the innkeeper’s daughter, and during the night her neck stretched and her face changed into that of Oyotsu. She angrily accused him of murdering her. The next morning the monk, regretting his evil deeds, confessed the murder of Oyotsu to the innkeeper. The monk also told the innkeeper what he had seen the night before. The innkeeper confessed that he, too, had murdered his wife for her money. He used the money to build his inn, and as a punishment his own daughter was transformed into a rokurokubi. Afterwards, the monk rejoined his temple, built a grave for Oyotsu, and prayed for her soul every day. What happened to the innkeeper’s daughter is never mentioned.
Source: Yokai.com, retrieved 08/16/2022; shared under Creative Commons and Attribution-NonCommercial-ShareAlike 4.0 International license.