The narrative unfolds amid a conflict between the Krakozhia Dukedom and the Grania Republic. Amidst the hostilities, a savior emerges for the Krakozhia Dukedom: a high school student named Souhei Yano. Two female soldiers, First Lieutenant Ruto and Second Lieutenant Haruka, arrive in tanks to disrupt Souhei's daily routine, soon joined by the enemy soldier Shachirofu. All three wield firearms without hesitation at his residence.