The origin of Nine Star Ki is unknown, but it can be dated to pre-historic China where Xia Yu (about 2180 B.C.), whose knowledge in water control and irrigation had introduced great order to his society, was made Emperor. 

While Xia Yu was supervising his flood control project, he came across a giant tortoise, which had been symbolic of longevity and happiness. Under close examination of the tortoise, Xia Yu noticed there were markings on the shell. The markings also appear to be positioned in different octagon partitions that are common to the tortoise shell pattern. The diagram is known as the Luo Shu (The Book of Luo). The Nine Star Ki is an attempt to unify the understanding of human interactions and events using numbers on nine chambers of the Luo Shu.

While I-Ching is an ancient Chinese philosophy, and Zi Wei Dou Shui is regarded as the Chinese Astrology, Nine Star Ki is better known as the Japanese Astrology.

What is Nine Star Ki - the Japanese Astrology?
Nine Star Ki is really interesting, it involves life forces similar to the hard and soft aspects in Western Astrology; it also uses numbers to derive its personalization and reading similar to the western Numerology; while the numbers are associated with Houses in a chart that are directional (North, South ... etc are pinpointed), it also shares the Feng Shui fundamentals that is based in I-Ching. One can say that Nine Star Ki is truly an embodiment of all ancient philosophies.

Using I-Ching where the Yin and Yang are two opposing forces predominantly found in life, the ancient sage of Nine Star Ki introduces a life force or Ki, which is the interaction of Yin and Yang. The ancient sages also saw that all things in life underwent five transformations to complete a cycle. The five transformations are represented by five elements, namely Wood, Fire, Earth, Metal and Water. The analogy is that Wood gives Fire; when Fire is burned, the carbon settles to Earth. Earth allows growth and maturity of life where the sense of certainty is represented by Metal. Death is symbolic of Metal being dissolved by Water. Water also gives life and enables the growth of  tress or Wood, thus completing the cycle. Studying the interaction of the elements allows us to analyze one's personality based on the forces derived in one's personalized chart. The resultant analysis pertains to one's birth data, thus the natal analysis.

In forming the Ki chart as in the Book of Shu, the ancient sages represented the nine Houses by the elements, numbers and directions (north, south etc.). Using Feng Shui (wind and water) fundamentals, the ancient sage refined the study of influences of earth and nature on humanity in Nine Star Ki to enable the understanding the nature and directional effect with respect to the time element. Since the time element is introduced via a particular date that is superimposed on one's natal chart, the recommendations of which direction is best for one to travel and its effect is available in Star Nine Ki as transit analysis. Such personal and dynamic analysis is most popular in modern day Japan.

How to cast a Nine Star Ki chart
Using one's Julian calendar birth date (the western calendar that we are accustomed to), the years and months are translated into a lunar calendar. With the injection of numerology methods, the year and month are translated into numbers. The numbers result in the plotting of a personalized chart in the form of an octagon. There are nine palaces with fixed directionals (ex. North, South East..etc.) in the personalized chart. Associated with each palace of the octagonal chart, elements such as Fire, Earth, Water, Metal and Wood are determined. The Ki forces of one's chart are studied based on interaction of elements that control and suppresses the other or giving rise to another. Personality traits are thus read based on such chart interpretation.

There are two significant numbers in Nine Star Ki: an individual's year number and month number.  Using a classical Nine Star Ki method based on birth data, an individuals year and month number can be extracted.  Charting methods require that the year number reside in the Central Palace.  The remaining palaces are then populated in accordance with these Nine Star Ki charting methods.  Based on the population of these palaces, one's natal chart can be derived.  A trained Nine Star Ki Astrologer can then reference the natal chart along with an individual's birth number to develop a personalized reading.