Momoha Kaguki, a young lady from one of the most prestigious schools in Japan, who is suddenly told by her childhood friend Sengen Amaya that he has a girlfriend and that he wants to keep his distance from her. Momoha is perplexed that Sengen, who is one year younger than Momoha and has always gotten along well with her despite being a plebeian, has a girlfriend, and she is determined to have a boyfriend of her own.