Sei Izumida

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...

The strangled dead body of Hiroshi Hatano, accounting section chief at the longstanding apparel company Edaka International, is discovered in his apartment in Tokyo. At the scene, Inspector Totsugawa and Detective Kamei find out that a mysterious email stating "I'll be riding the Super Ozora 5 tomorrow" was sent to the victim's cell phone the night before. The sender, Manami Furuya, an employee of Edaka International's Planning Section, has strangely terminated her cell phone service and hasn't shown up to work that very morning. Immediately afterwards, Totsugawa is astonished to receive a report from the Hokkaido police stating that the body of a man, stabbed to death, has been found on the Super Ozora 5 limited express. The man is Yuuki Nakamura, a bar employee from Tokyo, who seems to have flown from Haneda Airport to Sapporo and then boarded the Super Ozora 5, which connects Sapporo and Kushiro. Totsugawa has the feeling that this can't be a coincidence...

Hiroshi Hamano, a professor at a medical university, is found dead. Going by the results of the autopsy, it appears he committed suicide by jumping off a roof, but going by eyewitness testimony and physical evidence at the scene, Detective Kamei suspects murder. A ticket for a train trip around Japan is found in the professor's pocket. However, nobody then could have known the shocking truth hidden behind the tour the dead man was supposed to attend...

Nami, the young madam of a well-established hot spring hotel in Kotohira, is reunited with her childhood friend Kana who has come to participate in an art auction. However, when people with links to the auction start getting killed one after another, Nami sets out to find the criminal with her detective husband Ryohei.