One day in early summer, an elderly man over 90 years old visits a police station and confesses to his nephew, a detective, that he has killed someone. He begins to talk about a special facility at the end of the Pacific War.

It is a special secret facility where a doctor working on atomic bomb development and a man who can predict the war situation with 100% accuracy live.

Navy officer Yomogi hires an American intelligence officer Tsuda, a Hawaii-born Japanese American, as a double agent and brings him to the facility. Yomoi plans to invite a Japanese-Soviet Soviet ambassador and army officer Morimoto to the facility in order to advance peace negotiations with the Soviet Union as an intermediary. Meanwhile, the United States is suspicious of Tsuda's presence and sends Tanaka, also a Japanese-Hawaiian.

What was Yomogi's best friend Minakoshi thinking when he quit the military?

What will the white carrier pigeon that Ai sends to the future convey?