Keizoku (1999)

They're both Buddy Cop dramas with male and female leads investigating weird, abnormal cases. Female leads are both weird and quirky and decided to become police officers to follow in their fathers foot steps. Male leads are both disillusioned with the criminal justice system. The writing and character dynamics are very similar.

Quirky characters, creepy cases, similar off-beat and dark atmosphere. Both also have male x female duo with great chemistry

Psychometrer Eiji is one of the dramas that Tsutsumi Yukihiko directed before Keizoku. Its also the drama that influenced the creation of Keizoku the most. Psychometrer Eiji is almost like a prototype for Keizoku and you can see the characterization and plot points that would be reused.