- Founded by Ito Ittōsai Kagehisa. The creator of the Ono faction (Ono-ha), Ono Jirōemon Tadaaki,
succeeded as the head of the main line after learning directly from Ittōsai.
The main line was named gOno-hah to distinguish it from other branches and factions.
Tadaaki went on to serve as the kenjutsu instructor of Tokugawa Hidetada, the second Tokugawa Shogun.
- Ono Jirōemon Tadatsune was the third son of Tadaaki. He was originally named Tadakatsu.
After studying under his father and succeeding him as the head of the main line, he took the name Jirōemon.
Tadatsune taught many other students in addition to serving as the official teacher of the House of Tokugawa.
- Ono Jirōemon Tadao was the fourth son of Tadaaki. He was adopted by Tadatsune as his heir.
An alternate theory is that he was a hand-picked student. He studied under Tadatsune and
received the full transmission of Ittō-ryū. He worked as an official kenjutsu instructor to the Shoguns Ietsuna,
Tsunayoshi, and Ienobu.
- Tsugaru Nobumasa, the fourth daimyo of the Tsugaru Domain, learned Ittō-ryū from Tadao
and mastered its deepest secrets. He was renowned for his accomplishments in both the military and literary arts.
- Ono Jirōemon Tadakazu, originally named Okabe Sukekurō, changed his name to Tadakazu after being adopted
as Tadaofs heir. Learned Ittō-ryū from Tadao and succeeded him as the head of the main-line school.
Tadakazu had many other students aside from the Tokugawa Shoguns.
He passed on Ittō-ryū to Tsugaru Tosa-no-Kami Nobuhisa, bypassing his own son.
- Tsugaru Tosa-no-Kami Nobuhisa was the fifth daimyo of the Tsugaru Domain. Through an official proclamation,
he received the full transmission of Ittō-ryū as the patrilineal heir of Tadakazu.
Due to this decision, the official transmission of the main line of Ittō-ryū temporarily
passed from the House of Ono to the House of Tsugaru.
- Ono Jirōemon Tadahisa learned Ittō-ryū from Tsugaru Tosa-no-Kami Nobuhisa
but died before he had a chance to master the entire curriculum.
- Ono Jirōemon Tadakatafs father, Tadahisa, passed away while Tadakata was still young,
so he wasnft able to learn Ittō-ryū from him.
Unwilling to accept the fate of Ittō-ryū being severed from the House of Ono forever, Nobuhisa,
who by then had retired from official life and taken the name Sakaeō, taught Tadakata Ittō-ryū
as he grew older. By doing this, he facilitated the return of the main line of Ittō-ryū to the House of Ono.
- Ono Jirōemon Tadayoshi was a son of Tadakata. He learned Ittō-ryū from his father
and had many disciples.
- Ono Jirōemon Tadataka was a son of Tadayoshi. He learned Ittō-ryū from his father
and succeeded him as the headmaster of the main line.
- Ono Jirōemon Tadasada was a son of Tadataka. He learned Ittō-ryū from his father
and succeeded him as the sole heir of the school.
- Ono Nario learned Ittō-ryū from his father and received the full curriculum.
(The transmission of Ittō-ryū within the House of Ono ended with Nario.)
- Nakanishi Chuta Tsugusada learned Ittō-ryū from Ono Jirōemon Tadao and Tadakazu.
(The school he started later became the Nakanishi faction of Ittō-ryū.)
- Yamaga Sokō was taught Ittō-ryū by the founder of the Ono-ha, Ono Jirōemon Tadaaki.
(Yamaga Sokō taught military strategy to the Tokugawa Shoguns, the House of Tsugaru, and Ono Jirōemon Tadaaki.)
- Members of the Yamaga family, while maintaining ties with the Houses of Ono, Tsugaru, and Nakanishi,
served as official instructors of Ittō-ryū within the House of Tsugaru.
- After Japan entered the Taisho era, Sasamori Junzō received the full transmission of the main line
of Ittō-ryū from the Tsugaru and Yamaga families.
After consolidating the transmission materials he received from them, he assumed the position of the 16th headmaster (sōke) of Ono-ha Ittō-ryū.
- Sasamori Takemi studied under his father Sasamori Junzō and succeeded him
as the sole heir of Ono-ha Ittō-ryū, becoming the 17th headmaster (sōke).
- Yabuki Yūji studied under Sasamori Takemi and succeeded him
as the sole heir of Ono-ha Ittō-ryū, becoming the 18th, and current, headmaster (sōke) of Ono-ha Ittō-ryū.
Lineage of Ittō-ryū