Buddhist, Dr. Mikao Usui, is the founder of Usui Reiki. Throughout Dr. Usui’s study of medicine, psychology, and theology, he searched for heeling through a laying of hands.
Although Dr. Usui came from a strong Buddhist background, his passion was a healing method unattached to a specific religion so that the system was accessible to everyone. He studied all types of healing and worked many different professions before becoming a Buddhist priest/monk. During his training in a monastery, he went to a cave on Mount Kurama where he prayed, fasted, and meditated for 21 days. At that time, he saw ancient Sanskrit symbols that assisted him in the development of Usui Reiki. Dr. Usui then established the Reiki clinic in Kyoto.
For more information on Reiki, see the Resources below:
Essential Reiki: A Complete Guide to an Ancient Healing Art
by Diane Stein
Reiki for Life: The Complete Guide to Reiki Practice for Levels 1, 2, & 3
by Penelope Quest
International Association of Reiki Professionals: https://iarp.org/history-of-reiki/