Overhaul Rebirth is a phenomenal application of the Natsume-Style Form Refinement similar to the technique used by the feudal era Aya Natsume where excessive Ki inside a body rearranges the bone structure and organs. It was referred to as a miracle.
The theory behind the phenomenon is a common case to every person. The healing of a wound or injury and the formation of new muscles through working out are all considered to be cases based on the theory of the Overhaul Rebirth phenomenon. However, This phenomenon in itself is the case where such change happens a lot faster and changes the body's structure from the bones to the organs. This faster restructuring of the body is caused by the excessive amounts of Ki in the individual's body.
After such a phenomenon occurs the body shows great change in the aspect of functionality. The individual, on the other hand, feels the body to be lighter and more sensitive while the five senses are enhanced making it possible for the individual to feel and hear things that should not be possible under normal circumstances.