Hayato Izumi is intelligent, serious, and responsible—the perfect candidate to become student council president. But when the beautiful and busty Ui Wakana wins the crowd during her election speech by showering them with condoms and promising exciting reforms, Hayato drowns in defeat and reluctantly agrees to become her vice president. But just when he thought that the situation couldn't get any worse, president Ui suddenly barges into his home and announces their marriage. As it turns out, their parents had made a drunken promise decades ago that their children would one day become husband and wife. Naturally Hayato is against this, but Ui has the complete opposite reaction, and even wants to live with him! Will the upset Hayato and the overenthusiastic Ui be able to manage their school and marital life while keeping it a secret from the other students? Or will the two never come to understand each other's feelings?