Kobushi Kuroi, also known by the alias Black Fist, is a young Esper thief who appears in the anime Tokyo ESP. She possesses the ability to render herself and her surroundings invisible, a power she uses in combination with her exceptional boxing skills during confrontations. Her background is that of a self‑proclaimed phantom thief who announces her criminal acts in advance, seeking to build a notorious reputation. She is characterized by a large ego, a strong competitive streak, and a love for fighting, particularly against police or anyone willing to give her a good challenge. Her early motivations are driven by the desire for fame and notoriety through her heists.

In the story, Kobushi initially serves as an opponent to the protagonist Rinka Urushiba. After suffering a defeat at Rinka’s hands, she holds a grudge. However, her perspective shifts when Rinka’s father rescues her during a dangerous situation, causing her rivalry to evolve into a reluctant alliance and eventually a genuine friendship. She becomes a supporting ally to Rinka and other main characters, using her invisibility and boxing prowess in battles against common enemies. Her key relationships include her younger sister Kozuki Kuroi and the bond she forms with Rinka and Rinka’s father.

Throughout the series, Kobushi undergoes notable character development, transitioning from a self‑centered thief obsessed with making a name for herself to a more cooperative and loyal comrade. Her primary notable abilities are her ESP‑granted invisibility, which she can extend to objects, and her skilled boxing technique, allowing her to strike without warning while unseen.