From the RPG (page 107):
'Kizen' has two meanings:
1. The power which now permeates the Solar System and grants some individuals strange and unique powers.
2. An individual who has mainfested kizen abilities.
Kizen in Society
"The number of humans who have demonstrated kizen abilities is, at this point, still a very small minority."
"Most people in the Solar System do not yet know what to make of kizen."
"The governments of Earth and Gongen have not yet made up their minds about kizen"
Who Becomes Kizen?
"Anyone, it seems."
"...there are a small number of factors which are 'strongly correlative'. They do not appear in 100% of all kizen, but are common enough that they seem to be a large part of the puzzle.
They are: Personality, Genetics, Age."
Defining Kizen
"The type of power - Physical, Mental, Energy or Spiritual." These are the talent tree studies of thought. (italics is my own comments)
"Many kizen powers are active - they are turned on by an act of will... other powers, often but not always physical, are innate - they never go on or off, and require no kizen points to use..."
Late Bloomers
"The core rules for Player Character kizen assume they gain their powers shortly before play beins, when they are 1st level. However, many throughout the system had well-established careers when the Mumon Rift opened, and were well past 1st level when they manifested their powers..."
- Stratos