“Ten” can also be written as “Marubashi.” It is often compared to the image of a large round stone rolling vigorously down from a cliff, or crossing a log bridge without stopping.
The Concept of the Sphere
“Ten” is the theory of using the entire body as a sphere. This sphere performs infinitely varied actions, allowing one to avoid direct collisions, slip past or divert attacks, or draw the opponent into one’s flow. This principle is the basis for both body movement and sword handling.
This embodies the spirit of Fudōchi — “Immovable Wisdom.” An immovable mind does not mean becoming stiff and frozen, but rather continuously moving, never getting stuck, never clinging. This is the true essence of “Ten.”
San-gaku and Kukyo
San-gaku teaches waiting. The mind stays in a state of ken (suspended alertness) while the body remains in tai (poised readiness), drawing in the opponent’s attack and receiving it.
Kukyo teaches attacking. Against a watchful opponent, the mind remains in tai (prepared), but the body shifts to ken (active suspension), provoking the opponent’s movement, inducing them to strike, and thereby gaining victory. Both the will to attack and the openness to accept the opponent are necessary. Moving the opponent in this way leads to the Katsujinken — the Life-Giving Sword.
Tengu-sho and the Secret Sword
Tengu-sho is training in which offense and defense switch rapidly. Ken and tai transform instantly, allowing what was learned in San-gaku and Kukyo to be put into practical use.
The Secret Sword (Okugi no Tachi) goes even further, achieving a state where ken and tai are fully merged into one. As one progresses through San-gaku, Kukyo, Tengu-sho, and finally the Secret Sword, the “sphere” of bodily movement becomes progressively smaller. The level of abstraction grows higher, until in the Secret Sword, the movement of the sphere is reduced to a minimum within the body — leaving only the pure essence of “Ten.”
At this stage, invisible elements — awareness, spatial perception, and mental method — become dominant. Training in Yagyu Shinkage-ryu is, ultimately, the practice of i (position or state of being), cultivating a condition where even one’s intent does not collide with the opponent.
