(Japanese) Inner teachings.
This is the name of Level 2 taught in most Japanese branches of Reiki. Hawayo Takata was taught okuden (she actually wrote okudan in her diary but her spelling of Japanese words was inaccurate). The Usui Reiki Ryôhô Gakkai includes two grades within okuden. One is called zenki and the other is kôki.
This Japanese term signifies that you have begun working at this level — it does not signify that you have completed the level.