Usui taught it to one of his friends, Dr. Chujiro Hayashi, who in turn passed on Reiki to Mrs. Hawayo Takata.  This lineage is referred to as the "spiritual lineage of the Usui System."

There are three levels of Reiki according to the Usui system:

1st level: Just simply an introduction to Reiki.  There a student learns the History, Attunement, Hand positions, and participates in discussions with regards to Reiki.  Also, in the first level, it is stressed that Reiki is not a religion but merely spiritual energy channeled by God.  In addition to that, students learn that Reiki only works depending on both the channel and the receipient's willingness to accept healing.  In other words, the energy is only as potent as the either one will allow it to be.

2nd level:  This teaches a higher level of learning, attunement and a deeper level of Reiki energy.  Also in the second level are the three Reiki symbols that are introduced only to those that wish to venture forth into this level.  No one except those in this level know what the symbols look like.  This is done as to keep out skeptics and people merely studying it for curiousity.  Level one is supposed to weed those individuals out.  Only the serious pursue the second level.  However, the first symbol represents increased energy.  The second deals with Emotional Chakra, or emotional balance.  The third represents long-distance healing.  The third symbol teaches how to heal telekinetically, and not just with the hands-on healing.

3rd level: For the people who are not Reiki students, this part is the most vague, mainly because it is the most secret.  What is known is that in the third level one can begin teaching Reiki to others, and will be presented with the Master symbol.  The Masters must take on the highest levels of Integrity, Dignity, Respect, High Ethics and Professionalism when engaged in Reiki.  However, what is not known is what must be done to obtain that title of Master, or whether the third level is merely to signify a lifetime level and degree of Reiki.