Born in 1489 in Kashima, Hitachi Province (present-day Kashima, Ibaraki) as the son of Urabe Kakuken, a priest of Kashima Shrine. He was later adopted by Tsukahara Yasumoto, lord of Tsukahara Castle. Training in the Kashima sword arts from childhood, he set out on a warrior pilgrimage at age 17. Throughout his life, he is said to have fought 19 duels and 37 battles without ever being wounded, engaging in over 200 matches and slaying 212 opponents. He systematized the ancient sword traditions of Kashima Shrine into the Kashima Shintō-ryū, one of the wellsprings from which many later Japanese sword schools flowed. His technique centered on the secret principle called "Hitotsu no Tachi" (One Sword)—seizing the initiative and subduing the opponent with a single stroke. In the Sengoku era he was honored as a "Sword Saint," and his fame reached even the Ashikaga shoguns in Kyoto. He famously tutored the 13th shogun Ashikaga Yoshiteru, who became so skilled he earned the title "Swordsman Shogun." In his later years, Bokuden is said to have attained the philosophy of "Mutekatsu-ryū"—winning without fighting. When a brash young swordsman challenged him aboard a ferry on Lake Biwa, Bokuden lured the man onto a small island, then rowed the boat away, departing without a fight. He died in 1571 at age 83. Kashima Shintō-ryū continues to be transmitted at Kashima Shrine and holds a vital place as a fountainhead of Japanese swordsmanship.