Would you relate this to rei-ryoku-tai?
I don't think so. I'm not really familiar with the term. Is it Omotokyo? Many Japanese concepts sound similar to the Chinese concepts, but, they don't always go to the depth of detail the Chinese do. For instance, unification of mind and body or harmonization of mind and body. The most I ever got out of this in Japanese terms was to try to coordinate my mind and body to produce good tai sabaki and timing of movement.
What I've been getting into with the IP concepts is that my mind has really integrated with my body--not in the outer form of movement, but in being able to move within my body by "riding" the ki to become intimately aware of the inner assembly of my body.