The technique of the dual swords distinguishes itself by repetitive movements of the long and short sword. During these kata the opponent is threatened by one sword while the other sword is used to strike.
One of the greatest sword masters of Japan, Miyamoto Musashi (1584 – 1645), became famous for his use of dual swords in battle.
It is still unclear where Musashi leant to fight with dual swords. Certain sources state that he fought instinctively with dual swords in his fight with the Yoshioka family and later developed his own style,Ni Ten Ryu (2 heavens school).
But matter of fact is that Miyamoto Musashi also visited Tenshinsho-den Katori Shinto Ryu and trained there for a while.
Perhaps this is in part where Musashi learnt to fight with dual swords.
There are 4 kata in Ryoto, where the opponent is armed with a single long sword
Students are taught to fight with 2 different weapons simultaneously, and to use the long sword to cut and the short sword to slash the enemy.