and use the Jo from a divine vision some time after he was defeated by Miyamoto Musashi in a duel. In this vision, a divine being in the form of a child appeared, brandishing a stick (or log in one version) and proclaiming "know the solar plexus [of your opponent] with a round stick". The jō, however, as a simple staff or walking-stick cannot be claimed to have a single inventor and would have existed long before Gonnosuke. The jo, like its larger sibling the Bō (long staff), was never an effective weapon on the battlefield in comparison to the sword, spear and bow just to name a few. Although the jo and most other staves could be used to lethal effect when thrust at vital points of the body, when faced with a fully armoured opponent those vital points would in most cases be covered by armoured plating. As a result, there were very few ryu dedicated to the staff-arts in the warring era. There are several ryu that include jo-techniques in its system. One example is the jo-tradition found in the koryu art Tendo-ryu Naginatajutsu, founded in 1582. In Tendo-ryu, which uses the Naginata as the primary weapon, there are techniques with the jo that simulates a scenario where the naginata has been cut in two and the wielder has to defend himself with the staff-portion only. With the onset of peace with the start of the Edo period (1603–1867), the conflicts with heavily armed and armoured warriors became a thing of the past. In this era, the jo-art would come into its own against non-armoured samurai and other opponents. Various other martial arts also include elements of jōjutsu not necessarily related to Shinto Muso-ryu. One of the most famous promoter of the jo outside of Shinto Muso-ryu in modern times, and indeed in the martial arts community as a whole, was the founder of Aikido, Morihei Ueshiba. Ueshiba trained in a variety of ryu including Yagyu swordsmanship, but is not known to have trained in Shintō Musō-ryū. It is believed that Ueshiba used his training in sojutsu (spear) to create a set of techniques for the jo. (Ueshiba also used the longstaff bō to perform the same techniques.) Tachi (Ken) - The sword The Ken is featured in several Japanese martial arts. For more information see the Kenjutsu article. A regular bokken (or bokuto), the wooden practice