Bôkoku no îjisu is a Japanese novel written by Hiroshi Sakurazaka. The story follows a young man named Keiji Kiriya who finds himself stuck in a time loop, reliving the same day over and over again.
Keiji is a soldier fighting against an alien race known as the Mimics, who have invaded Earth and are threatening to wipe out humanity. Despite his best efforts, Keiji is killed in battle every day, only to wake up again at the beginning of the same day.
As Keiji continues to relive the same day, he begins to learn more about the Mimics and their weaknesses. With each iteration, he becomes a better fighter and starts to develop a plan to defeat the aliens once and for all.
Bôkoku no îjisu is a thrilling science fiction novel that explores themes of war, sacrifice, and the nature of time. It has been praised for its fast-paced action and thought-provoking storyline.