What is Yoseikan Sword?

Yoseikan sword is the sword curriculum of the Yoseikan, the school founded by Minoru Mochizuki (1907–2003). It comprises iai (drawing and cutting, from seated and standing positions), kenjutsu (paired sword against sword), and the Ken-tai Ichi no Kata, in which sword techniques are paired with their empty-hand counterparts. 

Mochizuki had trained classical sword methods before he took up aiki-jūjutsu. In his 1978 work Nihonden Jūjutsu, he writes that the claim that aikidō descends from the sword had long been repeated but never examined: 

Although it has long been handed down that aikidō originally issued from sword method, as to which form of sword method this technique came out of, not one single person had ever investigated it. Fortunately, I had acquired the old sword methods before I studied aiki-jūjutsu, so I was able to know the interrelation, at the level of technique, between kenjutsu and jūjutsu. 

The Ken-tai Ichi no Kata is Mochizuki's record of that relationship between sword and body.

The Yoseikan sword curriculum

Yoseikan sword is organised into five groups: 

Suwari Iai — Six seated iai kata: drawing and cutting from a seated position. 

Tachi Iai — Five standing iai kata. Mochizuki frames these as the swordsmanship of the chance encounter — the response to a sudden cut at the moment of passing on the road. 

Omote no Tachi — Paired kenjutsu from Tenshin Shōden Katori Shintō-ryū. Mochizuki presents one kata of the set, Itsutsu no Tachi ("the five cuts"). 

Gogyō no Tachi — The okuden (inner-transmission) kenjutsu: five forms — Mitsu, Yotsu, In, Sha, and Hotsu. 

Ken-tai Ichi no Kata — Five forms in which each sword technique is paired with an empty-hand technique. 

The six seated and the five standing iai together form the eleven base iai kata of the Katori line. The Yoseikan iai and Yoseikan kenjutsu both derive from this line; the Ken-tai Ichi no Kata is Mochizuki's own addition.

Lineage of Yoseikan sword

Mochizuki trained Tenshin Shōden Katori Shintō-ryū from 1928 as a member of the Kobudō Research Society (古武道研究会) founded by Jigorō Kanō at the Kōdōkan. This is the source of the Yoseikan iai and the Yoseikan kenjutsu. 

He also studied iaidō under Nakayama Hakudō at the Yūshinkan. This is a separate line and does not form part of the Yoseikan paired kata. 

In jūdō, Mochizuki was a student of Jigorō Kanō and Kyūzō Mifune; in aikidō, of Morihei Ueshiba. He records that Ueshiba once told him the Yoseikan was so different from aikidō that he "might as well call it aiki-jūdō." 

In his published notes, Mochizuki documents that he rebuilt the Katori solo iai as paired forms with an attacker, and that he revised individual kata — setting out, in each case, his reasons.

Sources

Minoru Mochizuki, Nihonden Jūjutsu (日本傳柔術), Tokyo: Kōdansha, 24 December 1978 — the Ken-tai Ichi no Kata in two forms (sword and body). 

Minoru Mochizuki, "Dō" to "Sen" o wasureta Nihon budō ni katsu (『道』と『戦』を忘れた日本武道に喝), Tokyo: BAB Japan, 15 February 1995. ISBN 4-89422-177-2 — the Ken-tai Ichi no Kata in three forms (sword vs sword, sword vs unarmed, unarmed vs unarmed).