When the hostile extraterrestrial creatures known as 'Savage' threaten humanity, the only defense lies in the powerful 'Hundred' weapons. Hayato Kisaragi, a survivor of Savage attacks, possesses exceptional compatibility with this technology. Invited to hone his skills at the renowned military academy, Little Garden, situated on a battleship, Hayato finds himself entangled in a web of attention from his female classmates. Amid rigorous training and looming battles, he navigates through various challenges to protect Earth from the menacing forces that have invaded it.