In Seireitou's own words, Seijūken is the highest level of the Gentle Fist style. It is a technique that allows Seireitou to control the entire radius of distance covered by the length of both his arms, by using a pulse of chakra from his centre to feel out the attacks that enter that "sphere of influence". He explains that it is meant for "occupying an enemy's territory". It is likened to a game of Shogi, in which it involves positioning yourself at a point where you are at the greatest advantage. It is seen as a large sphere of chakra, much like Eight Trigrams Palms Heavenly Spin, that surrounds the upper body of the user, and its size is directly associated with the user's mastery. With the usage of a weapon, the range of the Seijūken is heavily increased. Ryun could see no reasonable opening when engaging in hand-to-hand combat with Seireitou, feeling almost frightened at the size of the sphere of influence, to the point of declaring that he'd have to fight from a long range, stating that close-range fighting in this case would be suicidal. When mastered to a certain extent, according to Seireitou, the Seijūken can be reduced to a thin layer above the skin for the purpose of dodging the opponent's attacks at the last possible moment. An absolutely calm mind is necessary to use it, as even a slight degree of emotion will disrupt the technique. This is because the technique involves understanding one's opponent and feeling their rhythm.
The word, Seijūken, can be derived from two terms that relate to Seireitou. "Sei" is the nickname used by many characters he interacts with in the series, while "Jūken" is the japanese translation for "Gentle Fist", the fighting style of the Hyūga clan, of which Seireitou has mastered.