Kurogiri emerged from the corpse of Oboro Shirakumo, a deceased U.A. High student, transformed by Doctor Kyudai Garaki under All For One's commission. Garaki fused multiple Quirk Factors, including Oboro's original Cloud Quirk, to create the artificial Warp Gate ability. This process resulted in a sentient being composed of dark purple mist, marked by glowing yellow eyes and a protective metal brace encircling his neck and collarbone. Initially serving All For One directly, Kurogiri facilitated operations like the Underground Masquerade, enabling Quirk thefts and subject containment. His role evolved to overseeing Tomura Shigaraki's development as the League of Villains' second-in-command. Kurogiri exhibits calmness, formality, and unwavering loyalty to both All For One and Tomura. He consistently tempered Tomura's impulsiveness, offering strategic guidance during pivotal events such as the U.S.J. invasion and the recruitment of Stain, Dabi, and Himiko Toga. Despite his composed demeanor, he demonstrated a sinister willingness to endanger or kill heroes, dispersing U.A. students across disaster zones during the U.S.J. attack and turning Thirteen's Black Hole Quirk against her to achieve incapacitation. His Warp Gate Quirk generates dark fog capable of teleporting objects or individuals to precise locations, making him indispensable for the League's infiltration, retreats, and battlefield maneuvers. At U.S.J., he warped villains into the facility and later saved Tomura from capture by escaping Thirteen's Black Hole, showcasing tactical acumen by deducing and exploiting her inexperience. Following capture and imprisonment in Tartarus, Kurogiri underwent interrogation and research at Central Hospital. Pro heroes Shota Aizawa and Hizashi Yamada—Oboro's former friends—uncovered his identity and sought to reach Oboro's residual consciousness. Though initially dismissive of his past, Kurogiri displayed traces of Oboro's caring nature, particularly regarding Tomura's well-being. Spinner freed Kurogiri during the Final War to aid the villains. However, conflicts between his programming and Oboro's lingering emotions caused mental instability. In a critical moment, he saved Aizawa and Yamada from falling debris, warping them to safety; witnesses observed tears, suggesting Oboro's influence. Aizawa and Yamada subsequently harnessed this fragment of Oboro to redirect Kurogiri's Warp Gates, enabling hero mobilization against All For One. During the climax, Kurogiri overused his Quirk aiding heroes but reverted to protecting Tomura upon seeing him injured. He attempted to warp Tomura away, but his body deteriorated from the strain. With his final act, he created a barrier to shield Tomura from an attack, though it was thwarted. His last words apologized to Aizawa and Yamada, affirming his duty to protect Tomura—a reflection of Oboro's selfless nature persisting beneath his programming.