Kōei (煌影; Literally meaning "Bright Silhouette") is a conceptual armament that was born within Mukūrō's subconscious as he constantly drew in the chakra of individuals by way of his curse. Given the connection between chakra and the soul, it was surmised by Kazuhide and Zenjou that the constant absorption of a wide range of chakra sources opened up his soul and caused it to become hypersensitive. As a consequence, Mukūrō could unintentionally feel souls that existed around him, including those bound within human bodies. Of course, with training from his two comrades, Mukūrō has managed to cause the activation of Kōei to become an active trait, rather than a passive one.