The story happens over the course of one day. Twenty fishing boats from a country no one knows shoot at and take over parts of the Hateruma archipelago in the southernmost part of Japan. People from the Japan Coast Guard are being kept in custody. The Japanese government sends the Aircraft Carrier Ibuki and an escort fleet to the area because things are so tense. Ryota Akitsu (Hidetoshi Nishijima) is the captain of the Aircraft Carrier Ibuki, while Toshiya Niinami (Kuranosuke Sasaki) is the second-in-command. At 6:23 a.m., Japan is facing a day they have never seen before.