The hero who saved the world from an alien invasion, Takashi Shibuzaki, has only one dream: to live a normal high school life. After the war ended, Takashi was thrilled at the thought of finally fulfilling this long-cherished wish and decided to return to Japan to start his peaceful life. However, his war comrade Natalie, who hails from Northern Europe, unexpectedly moves into his house under the guise of "cohabitation." All Takashi wants is a calm and uneventful youth. Will this strongest returning soldier, who wishes to avoid both romance and battles, ever achieve the peace he longs for?