The Only One I Can't See 1992

A private lawyer (Hiroshi Mikami) who is infatuated with the widow of the Mamiya conglomerate (Emi Shindo) and aims for her inheritance. But he had multiple personalities. One day, university student Kawashima Megumi is mistaken for her older sister, Maiko. She is given a key to a coin locker, and finds inside the diary of Maiko's real father, a zaibatsu leader. Using her sister's name, Megumi gets close to the widow of the zaibatsu leader.