Reiki (the system) started in Japan. And was founded by Mikao Usui. Reiki the energy is as old as the universe as it is pure energy.
Reiki the system, is a hands-on healing system. It uses symbols, different hand positions, chakra and so on. Most people believe you have to be attuned to use Reiki. I do not, although I have been attuned to Level One and Level Two Reiki. NB: Reiki is the same energy we use in magick.
Reiki is commonly used to heal areas of the body or emotional issues. You place your hands on (or above) the body part that is being healed. But if the person has a serious emotional issue, the Reiki energy will first go to the spot of the issue, as Reiki is used for the highest good and the highest needs.
Great answer, I also practise Reiki and totally believe anyone can access the energy without being attuned by a master although I did pay to be attuned. The Universe is a mystical and magical place and the energy is there to be had free by anyone.
i'm not sure where you live, but my Occult shop specializes in Reiki magic, here's the link. they have classes if you're in the area, and if not, you could find books you could order in either online or from your own shop. personally i know nothing about Reiki, just felt like helping. http://www.odysseybooks.on.ca/