A relatively new title that is utilized for two different purposes. One is to signify that the student has completed both levels of a form of Reiki where the third Level is split in two. See Reiki Master/Practitioner.
The second purpose is that many Reiki teachers today do not believe that the term ‘Master’ is relevant as a description of what they do. There is the suggestion that it is arrogant to call one’s self a ‘Master’ after what is generally a brief course and if one has not mastered spiritual energy. The title Master/Teacher is meant to suggest that the person is in fact a teacher rather than a guru of some sort.
Although the title Reiki Master is still an accepted term for a Reiki teacher perhaps it is good to keep this quote from Yukiyoshi Takamura (1928–2000) in mind: ‘Anyone who refers to himself as a master, isn’t.’