When an extraterrestrial organism known as “Savage” attacks mankind, the only technology capable of combating the enemy is a weapon known as “Hundred.” A survivor of a Savage attack, Hayato Kisaragi is a teenager boasting the highest compatibility level with the aforementioned technology and as a result, is invited to master his skills at Little Garden, a prestigious military academy aboard a battleship.
Over the course of his intense training for the battle ahead, he immediately attracts the interest of multiple female peers and gets drawn into a number of incidents as he tries to fight against the creatures that now inhabit Earth and threaten its safety.
地球上的人類被一種名為「Savage」的神秘生命體侵略,唯一能對抗「Savage」的只有名為「百武裝」的兵器。為了利用「武藝者」待遇來替妹妹治病 的如月隼人,決定進入海上學園都市艦「Little Garden」就讀,並在那裡遇見一名陌生卻對他所知甚詳的室友艾米莉亞·漢密特。隼人、艾米莉亞和「Little Garden」的夥伴與「Savage」的戰鬥就此開始。