For a long time Reiju which means spiritual blessing or empowerment was thought to be the equivalent of the Western attunements, but now it is better understood and whilst ultimately they both can get us to the same place, a Reiju is actually very different from an Attunement. Reiju, sometimes called an Empowerment is a ritual that is performed by a Reiki Master on a student and is one of the Five Elements of the System of Reiki. Students either sit on a chair or in Seiza position while the teacher completes a physical and energetic ritual around him/her. The student may practice Joshin Kokyu-Ho breathing throughout the ritual, or just be open. By performing Reiju the teacher is creating a safe space for the student to draw as much Ki as he or she needs through the body. This is executed with the intent that ultimately the student will remember his or her connection to the Universe. Naturally, as the student draws the Ki, the benefits related to the energetic clearing/cleansing will also occur. The more Reiju given the better. You may receive 4 Reiju at level 1, 3 at level 2 and 1 at Master level. You should receive more Reiju along the way by attending Reiki support classes/groups with your Teacher.
The Western Attunements are a physical act using the reiki symbols to attune you and open your channels for drawing on and sending Reiki. The Japanese Empowerments/Reiju are a spiritual blessing, with no physical contact and no symbols. An energetic space is opened up between the practitioner and person receiving the empowerment, though the act is seen as no giver, no receiver, and no gift. This is not to say the Attunements don't work, they work very well, but they are not what was originally taught, and so it is important to be honest about this, and explain that they were brought in to connect the student quickly to the energy, and that in fact, the original system was about the teacher created for the student an energetic space, where the student could take from it what they needed at that time, rather being 'attuned' to something!
It is this Reiju that actually starts to change and increases your vibrational energy. Human beings are comprised of electromagnetic energy and the body vibrates at various rates that can be detected and measured by using an electro-myograph, the normal biological frequency of the body is 250 cps (cycles per second). However, research has measured frequencies of between 400-800 cps from Reiki healers.
Reiki is a specific band/frequency of energy for healing that works synergistically with Ki, it works at a higher vibration than other energy. Reiki cannot be seen by the human eye, as it vibrates too fast, it can however, be seen by using a Kirlian camera.
Your body needs time to adapt to this change in energy, and to do this the body goes through a 21 day cleansing/clearing process. This process may not always be easy, you may have a mix of emotions arise as you as you go through the healing process. Whilst old emotions come up, anger, upset, hurt and you release them, you are also raising your vibration as you become lighter. So, be kind to yourself during this process, explain to family and friends, if you feel angry or annoyed explain that you are healing and everything you are going through is what your body needs at this moment in time.
You may feel a variety of sensations, have visions, see colours or you may feel very little, during and after the Reiju. Everyone's experience of it will be different, and each time you have one, again this will be different, and there is no right and wrong way to experience it. The best way to experience it is to have no expectations of the process just let it happen and enjoy it.