Homunculus (2021)

Susumu Nakoshi, 34, once worked for an insurance company, but is now homeless, sleeping in a car and suffering from amnesia and an inability to experience emotions. One day, a medical student Manabu Ito convinces him to become the subject of an experiment, the essence of which is to drill a hole in his skull. Susumu agrees, but after the operation it turns out that when he closes his right eye, he sees homunculi with his left.