In a gym, a girl is pulling some pulleys, to gain arm strength, while three men and three girls watch a judo demonstration in the middle of the room. A girl wearing a sweater and shorts applies a succession of holds to a young man in a sleeveless undershirt and a black trunks: over the shoulder projection, arm lock, over the hip projection, sideways headlock and knee to the face, sacrifice fall followed by school-girl pin, kidney punching followed by a groin kick, sideways kick to the knee and a...