Shiatsu was invented by Tokujiro Namikoshi; he founded the first shiatsu college in 1940.
The characteristic of shiatsu as defined by Namikoshi is to apply pressure using only the fingers, palms and especially the thumbs on points that have been related to the central and autonomic nervous systems. Masanuga, who identified reflections of the acupuncture channels in the arms and legs, considered that shiatsu should a) involve the whole body, b) require a focused practitioner sensitive to the energy distributions of the body, and c) provide an extra dimension of connection and support (using both hands where one 'listens' and the other acts).
"Diagnosis and Therapy combined" is the claimed ability of the shiatsu "practitioners" to use their sensory organs (palms, fingers, and thumbs) to detect disharmonies in the energetic components of the body, (such as stiffness or slackness at or within its surface), and to perform routines to correct these problems. This combined diagnosis and treatment is the primary difference between shiatsu and Traditional Chinese Medicine such as acupuncture and moxibustion).