Soul-sensing abilities (魂感知能力, Tamashī Kanchi Nōryoku) refers to the branch of techniques from the power of seeing the souls of the living.
Originating from a special sense known as the "sixth sense", these abilities allow for being able to see and/or feel what is usually invisible to the naked eye, namely one's soul, their wavelength, and even madness.
The method, however, can vary dependent on the individual. For many individuals, notable human meisters, they develop special techniques in which allows the outright power to perceive the souls of others visually while others may have to rely on special weapon transformations that allow for such abilities (i.e Tsubaki's Mode: Chain Scythe and the Trap☆Star technique that senses souls via sound emitted from the chains).
However, these abilities also come with limitation and weaknesses; certain techniques that utilize these abilities make the user more susceptible to being affected by madness, as madness affects the sixth sense. Furthermore, the magnetic field on Lost Island also proved to distort soul-sensing abilities, with only the most keen able to utilize such abilities albeit with extreme difficulty.