Jinjitsu is a Japanese term used to refer to one of the 5 sekku which are days marking changes in the seasons. It will be further described in this section.
When it is pronounced as 'ninnichi,' it means the unit which refers to the volume of work or labor. It refers to the volume that a laborer covers in a day (8 hours).
Jinjitsu is one of the 5 sekku that mark changes in the seasons. It falls on January 7. It is also referred to as nanakusa (seven kinds of vegetables) no sekku because people eat 7-herb rice porridge on the day.
In ancient China, each day in the new year's week was designated as the day of a certain animal, with the first day as the day of the rooster, the second day as the day of the dog, the third the boar, the fourth the sheep, the fifth the ox, the sixth the horse respectively. It was prohibited to kill the animal on the related day. The seventh day was designated as the day of the human being, and punishment on the criminals was avoided on the day.
There was a custom to eat hot soup with seven kinds of vegetables, which was introduced to Japan and it eventually became the seven-herb rice porridge. Japanese people started eating the dish in the Heian period, and by the Edo period, it had taken root among commoners. It subsequently became the official event of the Edo bakufu (Japanese feudal government headed by a shogun) to have the dish on January 7, when all the warriors including the great general celebrated the day eating nanakusa rice porridge.
Jinjitsu is also supposed to be the first day in the new year for people to clip their nails. It is said that before clipping, bathing one's hands in the water with seven herbs to soften the nails makes one not catch cold throughout the year.