To dream of ninja stars represents conflict or division that is precise. Knowing exactly how to get rid of something or attack something you don't want.
Positively, ninja stars reflect your own ability to react to a problem with the perfect solution.
Negatively, ninja stars symbolize problems in life that are perfect in their ability to fail you. Something in your life that always seem to do exactly what you don't want.
To dream of seeing a ninja star sitting on a shelf may represent a perfect solution to a problem that you are waiting for.
To dream of a ninja represents an aspect of yourself that is expert, perfect, or adept. You or someone else that knows exactly what to do or deals with problems perfectly. Exactness.
Negatively, ninja in a dream may reflect feelings of fear that other people in your life always have perfect solutions to defeat you with ease. Fear of others ability to embarrass you with perfect defeat without warning.
Example: A woman dreamed of a vehicle with the license plate "NINJA" on it. In waking life she was separated from her husband preparing for a divorce and always felt that her husband was able to perfectly embarrass her by telling police or doctors that she was crazy because of her passionate religious faith.