Chinese Buddhism travelled across to Japan from the 7th century, and over the last 1,400 years has developed its own unique Japanese form.
A Japanese form of Buddhism called Tendai is said to have been a large influence on the teachings of Mikao Usui. Suzuki san, a Tendai nun and student of Mikao Usui, claims that he was a Tendai lay priest.
In the 1980s and 1990s, other forms of Buddhism such as Tibetan Buddhism were claimed to lie at the foundation of the system of Reiki. That is unlikely, however, as Buddhism originated in India and moved to China and Tibet independently of each other. Japanese esoteric Buddhism is a term that includes Mikkyô and Shugendô practices. Within these forms esoteric rituals involving mantras, mudras, and mandalas are used.