We often see TORII in our daily life, but are not so familiar with the question about what TORII is for. Much less so if non-Japanese. Let's a little deep-dive into TORII.
Split the world!
TORII is located in shrines and representing the sanctity of shrines for Shinto while temples are for Buddhism. TORII stands just on the line to split into the sacred area where shrines exist and the outside where we live.
In case of small shrines having no main halls and worshiping natural objects as gods (such as mountains and trees), TORII just stands alone. It tells us of the existence of the gods there. If you carefully drive in the mountains, you'll come across these small shrines very often.
What is the origin?
There was a god world called "Takamagahara" under supervision by the God of Sun called "AMATERASU-OMIKAMI". As her brother, "SUSANO-O" was so violent that she hid herself inside the rock door called "Amano Iwato".
As a result, the world lost the sun and everyone was in serious trouble with a lot of diseases and no crops.
Eight mils of gods gathered in front of the rock door, and discussed the solution to take her out of the door. They performed a lot of things such as dancing to draw her attention. One of the performances was to have a cock on a wooden bar crow toward her, the God of Sun.
The bar is said to be the origin of TORII. It is the combination of "TORI (bird)" and "I (be there)". Interestingly, cocks still crow in the early morning toward Sun even today. They are still in Ise-Jingu Shrine having 2,000 year-history even now.
Another tradition is that TORII derived from "TORI-IRU (pass through). The former may sound more attractive to us.
By the way, they failed in taking her out of the rock door with the cock. How could they succeed in getting the sunshine back, then?
It's funny. As soon as the God of Performing Arts started naked dances, other gods started laughing all at once. When AMATERASU-OMIKAMI slightly opened the door to see what was happening out of the hole, she was caught and taken out by a strong god. SUSANO-O was then banished from Takamagahara.
Japanese gods are very interesting and act like human being because there are eight mils of gods in Japan. They are very different from the foreign gods who are the absolute existence.
More than 100 kinds?
TORII has more than 100 kinds of designs but can be categorized into 2 groups, Shinmei (more straight bar type with less decoration) and Myojin (more curved design).
They are made from various materials, such as wood, stone, concrete and copper. Some are even titanium-made, which is durable for 1500 years. Amazing!
For more fun
It would be very interesting for you to compare the TORII designs during your visit to shrines. Further more, if you deep dive into Japanese gods who are the key players making Japan cultures, you will have more fun with their endless stories.