He is a Japanese swordsman from the Warring States period.
He is the founder of Itto-ryu and his student Tadaaki Oono is the sword instructor for Hidetada Tokugawa, the second shogun of the Edo period.
It is said that he never lost a single match in his 33 bouts using a serious sword.
He also taught his students that the sword is connected to the heart. In other words, if you practice the sword correctly, you will cultivate the right mind.
This idea is still the foundation of the Budo spirit more than 400 years later.