Angel Heart follows a young Taiwanese assassin codenamed “Glass Heart” who ends her life by leaping from a building, her heart being pierced by a metal fence. A heart transplant miraculously saves her, and during recovery she experiences strange dreams that lead her to Japan in search of her heart’s donor. She discovers that the donor is Kaori Makimura, a former partner of City Hunter’s Ryo Saeba. The author clarifies in the first tankōbon that Angel Heart shares only characters with City Hunter, but is not a continuation; the story takes place in a parallel universe and is unrelated to the original City Hunter series.