After a Taiwanese assassin known as 'Glass Heart' attempts suicide by leaping from a building, her heart is impaled by a metal fence. Surprisingly, she survives through a heart transplant. As she recuperates, she starts encountering peculiar dreams that drive her to Japan in search of her heart donor, Kaori Makimura. Kaori turns out to be the former comrade of Ryo Saeba, the City Hunter. The narrative in the initial tankoubon volume clarifies that Angel Heart shares characters with City Hunter but doesn't serve as its direct sequel. These events unfold in a separate parallel universe, distinct from the City Hunter storyline.