This technique is a fūinjutsu that the user places across their chest, and sets it to activate upon their death. It 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".