The founder of Mugairyu, Tsuji Gettan Sukemochi (also known as Heinai) was born in 1648 in what is now Shiga Prefecture .
When he was 13 he went to Kyoto to study Yamaguchiryu kenjutsu.
At the age of 26 he opened a Yamaguchiryu school in the 9th sector of Kojimachi in Edo (old Tokyo).
Tsuji realized the importance of spiritual education, and so he went to study Zen and Chinese philisophy under monk Sekitan at Azabu Kyukoji Temple .
After monk Sekitan passed away, he continued his Zen practice under the second chief priest Shinshu, and at the age of 45 achieved enlightenment.
Gettan Sukemochi in 1693 founded Mugairyu. The name "mugai" was taken from a poem penned by the late Sekitan:

Ippo jitsu mugai Kenkon ichijoo e Suimo masani mitsuni osamu Dochaku sureba hikari kiyoshi

Due to 20 years of spiritual dedication, Gettan was known not just as a master of the sword, but also as an enlightened zen philosopher and scholar. At Kyukoji Temple he was often in contact with many powerful lords of the time, including the Lord of Ogasawara Sado, Sakai Kageyu Tadataka, leader of the feudal Umayabashi clan, and the leader of the Tosa clan, Yamanouchi Toyomasa. Because Gettan's house was destroyed in the 1695 fires of Edo , the exact number of his disciples is unknown, but it is known that in the 14 years to 1710 his students included 32 households of major lords, 156 disciples of high rank, and 930 other students.

When Gettan was 61 years old, at the discretion of Lord Sakai he was to debut in front of the fifth shogun Tsunakichi, but unfortunately Shogun Tsunakichi passed away before Gettan had an audience with him. However, for a masterless sword instructor to be invited to have an audience with the shogun at that time was an incredible acheivement.