How did I not know about the Angel Heart anime until today? I completely overlooked it for 8 years even though I really loved the manga. AARGH.
It's a parallel universe to City Hunter where City Hunter/Ryo's wife Kaori has just died. A young Taiwanese mafia assassin, Glass Heart, has essentially just killed a man in front of his young daughter. This drives her to suicide, but her organization saves her and Kaori's heart is transplanted into Glass Heart. Glass Heart is haunted by images of a man and memories she doesn't recognize and travels to Japan to find out more. Ryo and Glass Heart meet and Ryo adopts her as his and Kaori's daughter.
It's essentially a version of City Hunter that explores the romanticized notion that heart transplant survivors can gain strong memories and emotions from their donor's heart. I like it because Glass Heart (renamed Xiang Ying) is not even remotely Ryo's romantic interest (which you might've expected) and therefore it didn't degenerate into a trashy romcom.
And, y'know hot Taiwanese hitman chick.
Oh yeah, and City Hunter's good if you like old beat-cop/city detective-y stuff.
EDIT: crap, it made me cry T-T