During this time Dr. Usui went to mount Kuruama to meditate for 21 days, while fasting and exercising. Later, while descending the mountain Dr. Usui was stunned by a light ray shinning into his third eye (the area in the middle of the forehead above the bridge of the nose). This light was accompanied by a vision of him doing great healing work.

Subsequently he found out that he could heal people by mystical meditative ways. This was the beginning of Reiki. (Jesus is also believed to have used this type of healing).
Dr. Ushi died from a stroke in 1926. During his lifetime he had great success healing many people. He was very active with his daily healings, particularly after the earthquake in 1923 and all the injuries that this ensued. During these later years he trained Chujiro Hayashi to be his disciple and also become a grand master of the art.

After Dr. Usui's death, Chujiro carried on the teachings and healings and also introduced some hand movements to the therapy….

More at The Powers of Reiki Therapy Explained