Tatsuya Tagami transfers to Shirahana Academy, a newly co-ed school where he is the only male in his class. Driven by a delusional ambition to achieve world domination, Tatsuya decides that his first step is to impregnate every girl in his classroom. After seducing several classmates in the school gym, he convinces them to join his cause and bear his children to help him conquer the world.
Tatsuya continues his quest to impregnate his classmates as part of his grand plan for world domination. After asserting his dominance over Kaede and her followers, he further expands his harem by seducing the fortune-teller Yuko and the conflicted Kanae, who finally confesses her love for him. As he systematically claims more girls, Tatsuya edges closer to his goal while maintaining a tense dynamic with his childhood friend, Sayaka.
Tatsuya continues his mission to dominate Class 3F, first breaking the pride of Reika before turning his attention to the final girl, Sayaka Minase. Despite her insecurities and hesitation, Sayaka eventually confesses her love for Tatsuya with the help of Kanae, leading to a passionate encounter that completes Tatsuya's goal of impregnating every girl in the class. With his harem secured, Tatsuya is hailed as the "King of the World" during the school's cultural festival, marking the successful completion of his school domination.