Made in Japan, Last Room is both fiction and documentary. The occupants of the love-hotels and capsule-hotels tell their own intimate, dreamlike stories, interspersed with journeys through the archipelago's landscapes. Soon, these personal stories resonate with a collective history: that of Gunkanjima, the abandoned ghost island of Nagasaki, and then that of Japan as a whole.

High school student Nanami lives in Tokyo, Japan. She waits for Halloween because she enjoys dressing up in costumes with her friends. One day, Nanami’s father tells her about a mysterious serial murder case that takes place year on Halloween. Her father works as the chief editor at an occult magazine. At first, Nanami doesn't care about the serial murders, but frightening incidents keep taking place around her.

Shimada has been failing auditions one after another and worked as an extra in films. One day, his senior colleague invites him to audition for a company called "Friendship," where actors pretend to be the person the customer wants them to be. Accepting the job, he encounters a customer, Mio, who is planning terrorism.