This technique is a fūinjutsu that the user places across their chest, and sets it to activate upon their death. The technique releases four symbols from the user's body that then forms a large, black sphere around them. Anything caught inside the sphere's area is then drawn in and sealed within the user's corpse.
The name and appearance of this technique are a reference to the Chinese "Four Symbols", known as 'Si Xiang', which are produced from yin and yang, and act on the ba gua. These symbols are named: 'lesser yin', 'great yin', 'lesser yang' and 'great yang'.