Cowrie Shell of the Swallow

The Cowrie Shell of the Swallow (燕のカギュ貝, Tsubame no Kagyūkai) technique is an extension of the Rabbit Goddess Technique user's Byakugan, which is required to have been matured to the point that it can perceive all things in the universe as flows of energy. Because Kaguya's chakra is considered to be the most potent of all sources of chakra that have ever existed or ever will exist, as it was born directly from its originator, the Shinju, all forms of chakra succeeding it are connected to her will in some way; whether by indirect or direct means, the latter of which would include ancestry. Chakra, itself, is born when the spiritual and physical energies, which are found in the mind and body's cells of its user respectively, are molded together. With this technique, it becomes possible to invoke this connection and literally perceive elements, traits, and qualities within one's mind and body. Emotions can be perceived with ease, including but not limited to negative emotions, a target's mind can be read to learn everything that target knows and thinks, the composition and statistics of a target's physical body and capabilities can be derived within seconds, and so on. Alone, the scope of this technique's influence is limited solely to those that possess chakra that was acquired from the original source of chakra, but when combined with the power of a mastered Byakugan, it becomes possible to extract the aforementioned information from any form of energy, including that of natural energy.

The only theoretical method of preventing this technique from perceiving a target's mind, thoughts, and emotions would be to completely close off one's heart from the user of the technique. However, when engaged in the heat of battle, even for the most seasoned warriors, this becomes an almost impossible feat to accomplish, let alone something that many individuals ever learn to do in the span of their lifetime.

Trivia

 * This technique is inspired by the concept of cowrie-shell divination.