Detective Kamei of the First Investigation Division receives a request from lawyer Shinichi Nakamura, the son of his deceased close friend, to re-investigate a car accident. Akiko, the wife of Yasuo Furuki, a painter from Hakone, died in the accident 5 months earlier by crashing into a guardrail. Nakamura's client, Akiko's younger sister Yuki Izeki, suspects that she was actually murdered by Furuki for insurance money. Overwhelmed by these thoughts, Yuki had sent an email reading "I'll never forgive that man. I'm going to kill him and avenge my big sister," announcing a murder to Nakamura. In the middle of their conversation, Nakamura receives a call from Hakone PD confirming that Yuki had turned herself in that morning...