Ghost Walker (鬼門 遁甲) is a specialized branch of Mental Interference magic. It is an Ancient Magic that manipulates the vectors. Based on the user's wishes, this secretive magic can redirect other people's attention to the desired location and people with their vectors scrambled will never locate their target. Much like someone who intends to walk straight forward but is actually walking in circles, or maybe seeing a carriage plainly in walking distance but is never able to catch up. 
This magic is also called Kimon Tonkou or Kimon Tonkouno-jutsu. Kudou Minoru describes it as follows:"It is a magic art from the continent, the art of Kimon Tonkou, in essence is Spirit Interference Magic that derails orientation."