Ryūha Koei Sōgetsu (流派湖影蒼月, Ryūha Koei Sōgetsu) is a specialised technique used by Rintaro and presumably his father, which allows for the utilisation of the body's maximum potential and enables Rintaro to employ several high-level techniques in order to avoid becoming sexually aroused. The true purpose of this technique is to achieve a clear mind, and a silent and serene heart.
In order to master Ryūha Koei Sōgetsu, Rintaro was forced to spend ten years of his life training vigorously deep in Mt. Fuji's forests under the tutelage of his father. Each Way of Ryūha Koei Sōgetsu required its own special training in order to strengthen parts of the body or hone certain skills such as balance and accuracy. Specifically, it appears as though strength training was required to achieve Kogaku no Gyō and balance training for Jakuyoku no Gyō and Rōsen no Gyō.
After enrolling at Nangokuren High School, Rintaro quickly found himself relying on his training more than he had anticipated. After only the first few days, he had already been forced to use a wide variety of techniques to avoid danger or defeat his opponents. The strength of his Ryūha Koei Sōgetsu has been shown to be capable of impressing the Dragons of the school, with Ayane requesting that he personally train her. According to what Rintaro had informed her during their first training session, to master Ryūha Koei Sōgetsu is to be able to project the techniques of Shinrabashou, (the Universe, and All Things of Nature). Quite literally, Rintaro's techniques mimic that of animals and how they interact with the Elements of Nature.
Each way is focused on using a particular body part or method for attack, defense, and mobility. Kogaku no Gyō and Jakuyoku no Gyō appear to utilise the body's strength in the arms and upper body, to the extent that large mounds of earth can be moved or powerful gusts of wind can be generated from single strikes. Rōsen no Gyō on the other hand utilises the body's legs, allowing the user to achieve speeds high enough to move unnoticed by the average person, or kick projectiles with enough power and accuracy to disable somebody's movements. Other Ways have demonstrated extreme movements, tactics and sometimes even seemingly impossible methods by human standards.