Her Immortal Vengeance

In his old age, Linden Chase holds a special 'funeral' for himself while he is still alive. At the funeral, an 'uninvited guest' arrives. She looks to be 20 years old but addresses Linden Chase as an old friend. Astonished, Linden Chase immediately recognizes her as Autumn Shen, his Idealized Love from 50 years ago, who hasn't changed at all in 50 years.