In So Jutsu the longest weapon of Tenshinsho-den Katori Shinto Ryu is used.
The correct name of the spear, in Japanese, is Yari. Unlike the other arts like ken-jutsu, bo-jutsu and naginata-jutsu the name differs and the word “so” is not used to refer to the weapon
In the earlier days of the feudal age, the spear was the main weapon among the lowest class of samurai (ashigari). However in the days of the Tokugawa shogunate (1603 – 1863) the Yari gained popularity among the higher classes.
The spear is a weapon that plays a prominent role in Japanese mythology.
After the gods ordered deity Izanagi and his wife Izanami to create the world they deliberated, standing on a rainbow, and asked each other: “Would there be land down here?” With Ame no tamaboko (a divine spear set with jewels) they trusted downward and hit the ocean floor. When they withdrew the spear water that dripped down started to solidify and formed the first islands of the Japanese archipelago.
So jutsu in Tenshinsho-den Katori Shinto Ryu consists of 6 kata and use all movements that can be made with a spear. The most important movement with the spear are the ‘spirally-thrusts’ towards the enemy armed with a sword.