The film begins after the events of Episode 3, when Kisaragi had perished. The Mikawa Fleet (Furutaka, Aoba, Kako, Kinugasa, and Tenryuu) is now engaged in a Night Battle. Choukai uses Searchlight and takes medium damage, but they eventually prevail. A New Fleet Girl emerges from the sea after being "dropped." Kisaragi is the name. Kisaragi is returned to the temporary base in the Solomon Islands, but she is suffering from PTSD and amnesia, unable to recall anybody from the anime save Mutsuki...