Ryoichi Yoshimori is a university student. His girlfriend Kyoko Sawada is older than him, but he enjoys his time with her. After Ryoichi Yoshimori proposes to his girlfriend, she suddenly disappears one day. Several days later, he finally sees her again but she has no memory of him. Ryoichi Yoshimori is stunned, but he suspects her memory loss is related to the Kiokuya rumor. A person named Kiokuya is reputed to erase the memories of people. He talks to Chiaki Takaharu, who is a lawyer and attended the same university as him, about his situation. Ryoichi Yoshimori searches for the cause of Kyoko Sawada’s memory loss and gets help from childhood friend Maki Kawai and Chiaki Takaharu’s assistant.