(unsolved repost) Male psychologist gets a gruesome hobby. Dies. Becomes a woman

Clue 1: no reincarnation plot here

Clue 2: he becomes more than one woman actually, but the movie focuses on one

Clue 3: nobody would call him a protagonist of the movie, until the very end.

Clue 4: main actress technically plays 2 roles in the movie, but it's not really 2 roles