This paper discusses rapid advances in the efforts of the scientific world to understand what Qi is. "Qi" is, I accept, an unknown energy or an information-communication system that facilitates mind-body interaction, however we can not explain those phenomena theoretically. There are many ways to explain those phenomena, but we must first overcome the "Cartesian cut" between mind and matter. "Endo-obsevation theory" has recently been attracting considerable attention as a new paradigm in the science of complexity. This theory explains that matter -elementary particle- is based on the same concept as the mind. This paper gives a perspective on the implicit possibilities to understand Qi and mind-matter interaction using this theory.