Shimenawa Rope (注連縄)

The Shimenawa rope (sacred straw rope) is a ceremonial article of significance in Shinto and, the rope has religious meaning when adorned with shide (zigzag shaped paper talisman).
Shimenawa ropes are also called '7-5-3 ropes.'

Summary

In current day shrine based Shinto, the rope takes the role of and demarcating the shrine and precincts from the every-day world. Also, the surrounds of the shrine and places where deities reside are enclosed by Shimenawa ropes. Consecrated ground falls within these confines and, the ropes are a spiritual cleansing barrier warding off misfortune and evil. As Mitamashiro (revered deity spirits and objects) and Yorishiro (objects representing divine spirits) the ropes convey a sense that the gods can reside in that location.

In Shinto of ancient times, consecrated ground was eternal, whereas this world was a transient representation of the real world. The Shimenawa rope represented the border and barrier between those two worlds and in some situations signified a prohibited area. Shimenawa ropes are hung around: places where portable festival shrines are stored, reef outcrops in the sea, unusually shaped rock formations etc.

Meotoiwa (pairs of rock outcrops near each other) are well know examples of this practice.

These form one type of Shimenawa rope which symbolizes a barrier warding off evil and misfortune. From among the Ozeki (second highest rank) of Sumo wrestling, only particular select wrestlers are to be permitted to tie the Shimenawa rope that goes around the waist of the Yokozuna (grand champion).

Currently, places where lightning strikes (in particular when in rice paddies) are cordoned off with green bamboo from which a Shimenawa rope is then strung around. It is the custom in various regions of Japan to then pray for a bountiful crop.

Origins

Japanese Mythology

The Shimenawa myth has its origins from when Amaterasu Omikami (the Sun Goddess) was removed from the Ama no iwato (Cave of heaven), Ame no Futotama no Mikoto (one of the gods in Japanese mythology) strung a Shimenawa across the cave entrance to prevent the cave being entered again.

Beliefs related to the rice harvest
Beliefs related to the rice harvest are a fundamental thread running through Shinto.

Worship of nature has existed since ancient times in ancient forms of Shinto.

Customs and traditions that accompany the rice harvest culture are thought to run deep.

Ancient Shinto

Religious beliefs that include beliefs that deities are enshrined in mountains and forests are called 'kannabi.'
Later on, mention was made of primitive shrines in forests and woods as well as on rock formations and mountains but, places where the deities ascended form the heavens and rested and places where deities resided and were worshiped were identified by being roped off with a Shimenawa.

Forms

Shimenawa come in many various forms: standard Shimenawa, ornamented Shimenawa, daikon (giant radish) Shimenawa, burdock Shimenawa, ring Shimenawa etc.

Daikon (giant radish) Shimenawa taper at both ends and, burdock Shimenawa are thinner at just one end.

Religious use of ropes other than in Japan. In the central southern part of Korea a similar custom called 'kumchul' (금줄/禁縄) exists.
Displaying Shimenawa
Forms representing the gods are displayed for worship in the new year. Those displayed in the entranceways of homes are called 'tamakazari,' those on display in the kitchen and bathrooms of a home are somewhat simpler and called 'wajime' (hoop ropes). Tamakazari differ from region to region in Japan however, zigzag paper talisman, bitter orange (Citrus aurantium) and fern with white-backed leaves (Sorbus japonica) are often used together in decorations.
Timing of Decorations
The first day for Shimenawa decorations is ideally thought to be the same as when New Year's pine decorations are put on show however, customs differ from region to region. Currently, decorations are commonly put on display after Christmas and up until the 28th. Putting up decorations between the 29th and 31st is considered bad luck. Decorations put up on the 31st are only up for one night which is considered rude to the incoming gods. The custom of the day decorations are taken down also differs from region to region. On January 7, after 7 herb congee has been eaten or, the after the 15th (the minor/former new year) is when decorations are removed.