For this subject's previous identity, see Oboro Shirakumo.
As his name implies, Kurogiri's entire body is made out of a dark purple mist, save for his eyes, which are glowing yellow. He normally wears a very elegant suit with a tie and has a metal brace that goes from around his collarbone to just below his eyes.
In his villain costume, he covers himself in his dark fog with only the metal brace around his neck being visible.
Kurogiri has a level-headed personality, which often serves to ground Tomura Shigaraki's immaturity. He is intensely loyal to both All For One and Tomura, having been created to watch over the latter. As a Nomu, Kurogiri is programmed to only obey commands from a select few and will remain silent towards any attempt to extract compromising information about the League from him.
Kurogiri is very polite and well-spoken even to his enemies, sometimes introducing himself in a formal manner. However, just like his fellow villains of the League, he possesses a truly sinister nature, having no qualms in putting hero students in situations where they would be tortured or killed. At the start of the series, he was often seen tending to a bar in the League of Villains' first hideout at Kamino.
It remains unknown how much of Oboro Shirakumo's personality Kurogiri has retained. However, in his conversation with Shota and Hizashi, Kurogiri expresses Oboro's caring traits, as seen when he would constantly worry about his charge and tried to immediately inquire about his status. Kurogiri himself has stated that he was not at all bothered by Tomura's personality and simply cared for his well-being, greatly shocking his former classmates on how he still retained this trait.
At the very least, he seems unaware or dismissive of his previous identity, although a small part of Oboro was able to briefly manifest himself thanks to Shota's efforts.
Tactical Intellect: During his battle against the Space Hero: Thirteen, Kurogiri created a portal in front of himself and opened the exit behind Thirteen, turning the suction power of her Black Hole Quirk against her, resulting in her back being torn and scarred. Kurogiri knew it would work because he realized that Thirteen was a rescue Hero, and thus deduced that she lacked combat experience and battlefield awareness.
Warp Gate (ワープゲート Wāpu Gēto?): Kurogiri's Quirk grants him the ability to create and manipulate a dark fog from his head and hands. This fog acts as a portal to another location. Whenever he produces a mass of the dark fog, it transports anything it comes in contact with to a location of Kurogiri's choosing. His Quirk is coordinate-based, so in order to use it, he needs to know the exact location where he is supposed to open the exit portal.
He can also create multiple exit points where the things that touch his fog will emerge, as shown when he stops the fight between Tomura, Dabi, and Himiko Toga and each of their hands appear in a different location.
This Quirk's usefulness and rarity makes Kurogiri an extremely vital asset to the League of Villains, as even Tomura, despite being angered with Kurogiri during the raid on U.A. High, did not dare punish him and had Nomu rescue him because he was the only way to escape.
Warp Gate is an artificial Quirk made with a combination of several Quirks, with Oboro Shirakumo's Cloud used as the base factor. It is unknown how many Quirks besides Cloud have been used to make Warp Gate.
Neck Brace: Kurogiri wears a metal brace around his neck to help defend a vital part of his body that can't generate his protective dark fog. This item also appears to hold him back from leaking out specific info about the League towards the Heroes.