I studied and graduated from the Amma Institute in san francisco back in the early nineties. They taught Amma massage exclusively. amma massage follows a strict kata, (form). the hour version covers 140 tsubos,(points) along the chi meridians with 25 hand techniques. we work our lines away from the heart.
much of the technique is a method in which the thumb is applied to the point in a four count rhythm, each successive press going a bit deeper. there are more general pressures applied at first to "open" an area up, (also a way of announcing an intention to begin to work in that area of the body, etc.) it is a comprehensive, invigorating massage that covers the whole body except the genitals and is traditionally done through a sheet.
i have never experienced a more thorough massage and have had clients cry, get angry- feel various things during and after the massage.
learning and practicing amma changed my life for the better. if you can find a practitioner that still gives a traditional Amma massage i highly recommend giving it a try. many people claim that they feel the affects of an amma session for weeks after.
traditional japanese healing (and other) arts were made illegal after mccarthy came in at the end of WW II. in order to continue practicing Amma, (at that particular time most of these practitioners were blind) practitioners incorporated some western massage techniques and began to call what they did shiatsu which became more well known from then on.
amma has its roots in 5000 years of japanese (and chinese of course) medicine. chinese doctors, before they learned to learn about applying acupuncture needles would learn how to do amma. the points covered are the same points that acupuncturists follow.