In the images above, Ohsaki Sensei is performing a type of osae waza, or "pinning technique," that is found in varying forms in several versions of jujutsu. The idea is to immobilize the attacker using a painful wrist bending action, along with superior body positioning. In Daito Ryu aiki-jujutsu this sort of technique is sometimes called ippon dori, in aikido it's ikkyo, Hakko Ryu jujutsu calls it shodan osae dori, and in Saigo Ryu it's known as ude osae waza.
It is possible to transfer the painful pressure of the hand on the opponent's wrist to one's foot, and pin the opponent with a single foot. This leaves the hands free to draw a sword or perform one of the ancient Japanese forms of rope binding. Ohsaki Sensei can been seen executing this ashi gatame, or "foot lock," above.
Ohsaki Sensei was born in 1948 in the Shibuya section of Tokyo. He was interested in budo as a child, and at the age of seven he began to study Kodokan judo. His instruction began at the Hatagaya Keisatsu Dojo, one of the numerous dojo sponsored by the Tokyo police department. These keisatsu dojo, or police dojo, are infamous throughout Japan for the severity of their training. His initial training began with soji, the ritualistic cleaning of the dojo. For some time, he was only allowed to clean and watch his sempai (seniors) practice. Eventually, having proven his sincerity, he began learning safe falling techniques (ukemi) and later throwing and grappling methods.
Eventually, Ohsaki Sensei also began a comprehensive study of traditional jujutsu and classical Japanese weaponry, which he has excelled in for many years. A member of the Kokusai Budoin's prestigious kobudo, or ancient martial arts, division, he has demonstrated Nippon jujutsu at the Kokusai Budoin Sogo Budo Taikai. This important budo exhibition takes place early each spring at Otakumin Plaza in Tokyo. (Japan's Kokusai Budoin promotes all traditional Japanese forms of budo and bujutsu, and it is active in a large number of countries throughout the world.) Besides budo, Ohsaki Sensei has extensive training in Japanese forms of meditation and healing arts, along with a comprehensive background in shodo, the art of Japanese calligraphy.