Ryoichi Yoshimori, a college student, is in a loving relationship with his slightly older girlfriend, Kyoko Sawada. Their age difference doesn’t matter to them as they are deeply in love. However, after Ryoichi proposes, Kyoko vanishes without a trace. When she reappears days later, she has no recollection of Ryoichi. Determined to solve this puzzling situation, Ryoichi enlists the help of his classmate and lawyer, Chiaki Takaharu, along with his childhood friend, Maki Kawai. Together, they delve into the mystery, which might be linked to rumors about a person known as Kiokuya, who is said to have the ability to erase memories.