Re: Sagawa Yoshiyuki, Masaru Takahashi and Breath Training in Daito-ryu
Sensei would embrace anything with enthusiasm if he decided that it had martial benefits. Kiai-jutsu (気合術) and Saimin-jutsu ("hypnotism" / 催眠術) are good examples of this.
With regards to research into hypnotism, I heard Sagawa Sensei say, "I got to the point of being capable of instant hypnosis, but it's not as if it can be applied to anybody, and for instant hypnosis to work some preparation is necessary. Since it cannot be applied to a sudden attack I gave it up."