CURE

Cure is a 1997 Japanese psychological thriller written and directed by Kiyoshi Kurosawa, the film stars Koji Yakusho.

After a series of gruesome murders start happening around Tokyo, detective Takabe (Koji Yakusho) and Sakuma, a psychologist, are called in to figure out the connection, but it seems that it is only an X shaped wound carved into the neck of each of the victims. However, in all cases, the apparent murderer is found close to their victims but they don't remember anything about the crime.
When detective Takabe's investigations seem to lead nowhere, a strange man is arrested near the scene of one of the latest murders; the man seems to suffer from amnesia and surely has a strange effect on everyone who tries to talk to him.
Detective Takabe starts a series of interrogations to find out the man's actual connection with the killings, but the detective will find himself a little too much involved in the case and with the suspects apparent mermerizing and psychological powers.