Chikage Kuroba is the mother of Kaito Kuroba, the current Kaito Kid, and the widow of Toichi Kuroba, the original Kaito Kid. Before her marriage, she was the infamous phantom thief known as the Phantom Lady, also referred to as the woman of twenty faces from the Showa era. Her activities as a thief preceded those of her husband, and she was known for targeting large corporations and wealthy individuals who had acquired their fortunes through unscrupulous means, which earned her considerable public popularity. Unlike later iterations of Kaito Kid, her methods were notably more direct and even violent, as she would use horror-inspired tactics such as fake blood and a prop axe to frighten and incapacitate police officers and guards.

Chikage chose to end her career as a thief after meeting Toichi Kuroba in Paris eighteen years before the main story. During this encounter, she had been lured out of a two-year retirement by a false notice written in her name, which was a trap set by a group that manufactured fake gems. Toichi came to her rescue, and their escape involved a dramatic leap from the Eiffel Tower and a first kiss, following which he asked her to give up her life of crime. She accepted, retired from thieving, and married him, and he began his own career as Kaito Kid shortly thereafter. She is fully aware of the secret identities of both her late husband and her son, having discovered the hidden room and costume left by Toichi on her own.

In the present day of the series, Chikage lives abroad, primarily in Las Vegas, though she was originally based in Tokyo. She maintains a close, if somewhat distant, relationship with her son through frequent phone calls and video chats. Her personality is shown to be mischievous, as she often teases her son, such as when she revealed his fear of fish to his friend Aoko Nakamori. She has consistently given Kaito her tacit permission to continue as Kaito Kid, believing he must walk his own path, and has expressed pride in his abilities. Her relationship with her late husband remains a strong influence; she speaks of him with fondness and blushes when he is mentioned.

While Chikage largely remains a supporting figure operating from a distance, she plays a more active role on certain occasions. She has been shown to be investigating the mysterious organization responsible for her husband's death on her own. She also made a surprise return to Tokyo during the Midnight Crow incident, during which it is strongly implied she was secretly disguised as the phantom thief Corbeau, a new adversary. Her stated reason for this return was to test her son's resolve to continue his dangerous life as a phantom thief. After witnessing his determination, she was satisfied and returned to Las Vegas. She has an ally and caretaker in Toichi's former assistant, Konosuke Jii, with whom she frequently communicates to check on her son.

As the Phantom Lady, and later as a mentor to her son, Chikage possesses a range of skills that are on par with the Kaito Kid persona. She is a master of disguise, which earned her the "woman of twenty faces" moniker, and is highly proficient in acrobatics and showmanship. Her tactics as a thief included using surprise and theatrical fear, a style that differs from the more elegant and deceptive approach of her son. She has been shown to be a capable investigator, having spent years tracking the organization that killed her husband from her base in Las Vegas. One of the key elements of her legacy is her use of advance warning notices for her heists, a practice that was later adopted by both her husband and her son.