Dr. Mikao Usui was a Japanese doctor of religious studies who taught in Kyoto, Japan, in the late 1800s. He set out to learn how  Jesus, Buddha, and other enlightened beings could heal people with a touch. In his journey, Dr. Usui studied at monasteries and universities in Asia and the United States, learned several languages,  and pored over many ancient documents. After finding a set of symbols in a Sanskrit scroll, he set out on a 21-day fast atop Mount Kurama. On the twenty-first day of the fast, Dr. Usui was struck in the head by a beam of light that revealed to him much of the practice of  Reiki and the use of the symbols he discovered. Dr. Usui went on to practice Reiki across the country, lecturing and traveling extensively throughout Japan and training many Japanese students in using Reiki.

Among those trained by Dr. Usui was a retired Japanese naval officer and physician, Dr. Chujiro Hayashi, who founded a series of Reiki clinics in and around Tokyo in the mid-1920s. His first clinic is said to have been near the Imperial Palace and was frequented by royalty and court members, giving Reiki an immediate reputation and following among the educated elite in Japan. As the awareness and interest in Reiki grew, Hayashi opened more clinics and trained increasing numbers of students. He is credited with codifying the system of hand positions commonly used in Reiki practice today and is believed to have made many adjustments to Usui's system that made it less mystical, more easily explainable to doctors and patients, and more easily taught to the average student. Medical doctors would often refer complicated cases to  Hayashi's clinics. It was through such a referral that Hawayo Takata was first introduced to Reiki.

Mrs.  Takata was a Japanese-American woman from Hawaii who had numerous health problems, including a tumor, gallstones, and appendicitis. Her husband had died unexpectedly, and she was struggling to raise her two young children. As her health deteriorated, Mrs. Takata went to  Japan seeking medical help and, through a twist of circumstances, became a patient at one of Hayashi's clinics. After several months of treatment, Mrs. Takata's ailments healed, and she spent the following year as a student of Hayashi's with the intention of treating herself and her family. When she returned to Hawaii in 1936, Takata began to practice Reiki and was soon visited by Mr. Hayashi and his daughter.  Hayashi lectured in Hawaii, and when he left in 1938, he made Mrs.  Takata a Reiki Master.

In the 1970s, Mrs. Takata was invited to lecture and teach Reiki across the United States and Canada, including at the Trinity Metaphysical Center in Redwood City, California, led by Reverend Beth Gray. Beth and her husband, John Harvey Gray, studied under Mrs. Takata, and in 1976 John became the first Reiki Master she initiated in California and her third worldwide. In the 1990s, John often visited New York City to teach in Manhattan, where Brian Brunius met him, took first- and second-degree classes, and completed his Reiki mastery a decade later. John taught over 900 classes to more than 15,000 students and gave over 10,000 private sessions, becoming the longest-practicing Reiki Master in the Western Hemisphere. Until his death at 93 in January 2011, John and his wife, Lourdes Gray, ran The John Harvey Gray Center For Reiki Healing in Rindge, New Hampshire.

A Reiki Master Instructor, practicing and teaching Usui Shiki Ryoho, the Usui System of Natural Healing, for over 25 years. Brian’s study of Reiki began in 1995 when he enrolled in the first-degree course with his Master, John Harvey Gray. He consequently completed second-degree training in 1997 with John. In 2007, he founded NYC Reiki Center, a full-time private practice, when he committed to undertaking the Master's training with a student of John’s in New York City. Brian is an active member of The Reiki Alliance, an international community of Reiki Masters dedicated to the practice of Usui Shiki Ryoho.

Amilyo Escobar started his Reiki training in 2016 with Brian and completed his intensive 2.5 year Reiki Master in November 2023. He is the founder of ReikiDoes.