Musō Gonnosuke Katsuyoshi (夢想權之助勝吉) was a samurai of the early 17th century and the traditional founder of the Koryu school of jojutsu known as Shintō Musō-ryū (神道夢想流/神道無想流). He is perhaps most famous for his duels with the legendary swordsman Miyamoto Musashi.
Musō Gonnosuke Katsuyoshi was born into a samurai family, and like many other famous samurai and martial art founders, claimed to trace their lineage to a family of the classical period of samurai. His family is supposedly descendant from Kiso Kanja No Taiyu Kakumei , a retainer of the famous samurai general Minamoto Yoshinaka. Gonnosukes original family name is said to have been Hirano and that he used his given name of Gonbei in his early days. Unlike his future counterpart, Miyamoto Musashi, Gonnosuke was not a ronin (masterless samurai) through a defeat in battle such as is claimed with Musashi in the battle of Sekigahara, but had gone out on the road on a warrior pilgrimage to improve his skills in duels and by learning from different martial arts schools on the road. This was a common tradition called musha shugyō and many samurai wishing to develop their martial abilities undertook such travels frequently. Musashi had probably been a part of the losing side in the Battle of Sekigahara in 1600 and had since been a ronin and undertaking his own musha shugyō.
The Shinto Musō-ryū densho 伝書 contains a written heritage of the school, and also includes a list of the former headmasters, including the founder, and a list of the techniques. It also lists several of Musō Gonnosuke's teachers in martial arts, one of whom, according to the Makabei family records, was Sakurai Osumi-no-Kami, a lieutenant of Makabei Hisamoto (nicknamed Oni Doumu), who in turn was a student of the founder of Kasumi Shintō-ryū Kenjutsu. Gonnosuke also received other training from the Tenshin Shōden Katori Shintō-ryū-school, founded by Iizasa Choisai Ienao, and also that he received training in either Kashima Shintō-ryū or Kashima Shinden Jikishinkage-ryū, depending on the source. In addition to learning the ken (sword), he learned to use the bo (long staff), naginata (pole weapon), yari (spear) and various other weapons. Gonnosuke eventually received the rank of menkyo, a complete license with the authority to train and develop the art, from Katori Shintō-ryū.