Popular traditions credit the creation of the weapon known as Jo to the legendary Muso Gunnosuke Katsuyoshi, renowned as the only man who defeated the no less legendary Musashi Miyamoto, if only after being bested by Musashi first and his life spared. This event has found its way into literature and film- thanks mostly to the book "Musashi", by Eiji Yoshikawa. Other accounts appears in the Kaijo Monogatari (1629) and Honcho Bugei Shoden (1714).

The proper dimensions of the staff came to Gunnosuke in a vision, the story is told. Frustrated after having been defeated by Musashi in a duel, Gunnosuke retired to a shrine in Mount Homan, in Chikuzen (currently Fukuoka ken), where he meditated for 37 days, and performed purification rituals, and prayers. There, he experienced a vision that prompted him to create the staff with a length of four haku, two sun and one bu.

In a rematch, the shortened stick proved superior to the sword. This time, Musashi was the loser, and as he had done prior to Gunnosuke, his life was spared.

Although this story has been challenged often, and with many valid arguments, it shows without a doubt the versatility and effectiveness of the weapon, even against the sword, when properly used. The Jo has been successfully matched against the bo, the spear, and other weapons.

Although some other ryu lineage's claim to have knowledge of Jo techniques, Shindo Muso ryu (the style created by Gunnosoke) was taught only in the Kuroda clan.

Jo-do, its modern counterpart, is a relatively popular martial discipline that enjoys a well deserved reputation for elegance and fluidity.

Although the 12 kihon accepted by the Zen Nippon Kendo Renmei Jo-do bu are the best known and most widely practiced forms of Jo practiced today, several other Jo forms remain in existence.

The popularity of the Jo today is, without a doubt, due to Aikido's inclusion of this weapon in its curriculum. The Aikido Jo is not identical to the teachings of current Shindo Muso ryu, of course, but without dwelling on useless comparisons, the use of the Jo in any ryu of Bujutsu or Budo pays witness to the ingenuity and skill of Muso Gunnosuke. If we are to give credit to the story because, after all, imitation is the sincerest form of flattery.

Any budoka would benefit greatly by learning the techniques of this versatile weapon.